diff --git a/Documentation/config-labels.txt b/Documentation/config-labels.txt
index 3db621d..1aa6cd7c 100644
--- a/Documentation/config-labels.txt
+++ b/Documentation/config-labels.txt
@@ -238,7 +238,9 @@
 The `PatchSetLock` function provides a locking mechanism for patch
 sets.  This function's values are not considered when determining
 whether a change is submittable. When set, no new patchsets can be
-created and rebase and abandon are blocked.
+created and rebase and abandon are blocked. This is useful to prevent
+updates to a change while (potentially expensive) CI
+validation is running.
 +
 This function is designed to allow overlapping locks, so several lock
 accounts could lock the same change.
diff --git a/java/com/google/gerrit/index/query/QueryProcessor.java b/java/com/google/gerrit/index/query/QueryProcessor.java
index b318199..27ed72f 100644
--- a/java/com/google/gerrit/index/query/QueryProcessor.java
+++ b/java/com/google/gerrit/index/query/QueryProcessor.java
@@ -38,6 +38,7 @@
 import com.google.gwtorm.server.ResultSet;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -199,58 +200,67 @@
       return disabledResults(queryStrings, queries);
     }
 
-    // Parse and rewrite all queries.
-    List<Integer> limits = new ArrayList<>(cnt);
-    List<Predicate<T>> predicates = new ArrayList<>(cnt);
-    List<DataSource<T>> sources = new ArrayList<>(cnt);
-    for (Predicate<T> q : queries) {
-      int limit = getEffectiveLimit(q);
-      limits.add(limit);
+    List<QueryResult<T>> out;
+    try {
+      // Parse and rewrite all queries.
+      List<Integer> limits = new ArrayList<>(cnt);
+      List<Predicate<T>> predicates = new ArrayList<>(cnt);
+      List<DataSource<T>> sources = new ArrayList<>(cnt);
+      for (Predicate<T> q : queries) {
+        int limit = getEffectiveLimit(q);
+        limits.add(limit);
 
-      if (limit == getBackendSupportedLimit()) {
-        limit--;
+        if (limit == getBackendSupportedLimit()) {
+          limit--;
+        }
+
+        int page = (start / limit) + 1;
+        if (page > indexConfig.maxPages()) {
+          throw new QueryParseException(
+              "Cannot go beyond page " + indexConfig.maxPages() + " of results");
+        }
+
+        // Always bump limit by 1, even if this results in exceeding the permitted
+        // max for this user. The only way to see if there are more entities is to
+        // ask for one more result from the query.
+        QueryOptions opts = createOptions(indexConfig, start, limit + 1, getRequestedFields());
+        Predicate<T> pred = rewriter.rewrite(q, opts);
+        if (enforceVisibility) {
+          pred = enforceVisibility(pred);
+        }
+        predicates.add(pred);
+
+        @SuppressWarnings("unchecked")
+        DataSource<T> s = (DataSource<T>) pred;
+        sources.add(s);
       }
 
-      int page = (start / limit) + 1;
-      if (page > indexConfig.maxPages()) {
-        throw new QueryParseException(
-            "Cannot go beyond page " + indexConfig.maxPages() + " of results");
+      // Run each query asynchronously, if supported.
+      List<ResultSet<T>> matches = new ArrayList<>(cnt);
+      for (DataSource<T> s : sources) {
+        matches.add(s.read());
       }
 
-      // Always bump limit by 1, even if this results in exceeding the permitted
-      // max for this user. The only way to see if there are more entities is to
-      // ask for one more result from the query.
-      QueryOptions opts = createOptions(indexConfig, start, limit + 1, getRequestedFields());
-      Predicate<T> pred = rewriter.rewrite(q, opts);
-      if (enforceVisibility) {
-        pred = enforceVisibility(pred);
+      out = new ArrayList<>(cnt);
+      for (int i = 0; i < cnt; i++) {
+        out.add(
+            QueryResult.create(
+                queryStrings != null ? queryStrings.get(i) : null,
+                predicates.get(i),
+                limits.get(i),
+                matches.get(i).toList()));
       }
-      predicates.add(pred);
 
-      @SuppressWarnings("unchecked")
-      DataSource<T> s = (DataSource<T>) pred;
-      sources.add(s);
+      // Only measure successful queries that actually touched the index.
+      metrics.executionTime.record(
+          schemaDef.getName(), System.nanoTime() - startNanos, TimeUnit.NANOSECONDS);
+    } catch (OrmException | OrmRuntimeException e) {
+      Optional<QueryParseException> qpe = findQueryParseException(e);
+      if (qpe.isPresent()) {
+        throw new QueryParseException(qpe.get().getMessage(), e);
+      }
+      throw e;
     }
-
-    // Run each query asynchronously, if supported.
-    List<ResultSet<T>> matches = new ArrayList<>(cnt);
-    for (DataSource<T> s : sources) {
-      matches.add(s.read());
-    }
-
-    List<QueryResult<T>> out = new ArrayList<>(cnt);
-    for (int i = 0; i < cnt; i++) {
-      out.add(
-          QueryResult.create(
-              queryStrings != null ? queryStrings.get(i) : null,
-              predicates.get(i),
-              limits.get(i),
-              matches.get(i).toList()));
-    }
-
-    // Only measure successful queries that actually touched the index.
-    metrics.executionTime.record(
-        schemaDef.getName(), System.nanoTime() - startNanos, TimeUnit.NANOSECONDS);
     return out;
   }
 
@@ -332,4 +342,12 @@
     checkState(result > 0, "effective limit should be positive");
     return result;
   }
+
+  private static Optional<QueryParseException> findQueryParseException(Throwable t) {
+    return Throwables.getCausalChain(t)
+        .stream()
+        .filter(c -> c instanceof QueryParseException)
+        .map(QueryParseException.class::cast)
+        .findFirst();
+  }
 }
diff --git a/java/com/google/gerrit/proto/BUILD b/java/com/google/gerrit/proto/BUILD
new file mode 100644
index 0000000..48185d6
--- /dev/null
+++ b/java/com/google/gerrit/proto/BUILD
@@ -0,0 +1,14 @@
+java_binary(
+    name = "ProtoGen",
+    srcs = ["ProtoGen.java"],
+    resource_strip_prefix = "resources",
+    resources = ["//resources/com/google/gerrit/proto"],
+    visibility = ["//proto:__pkg__"],
+    deps = [
+        "//java/com/google/gerrit/reviewdb:server",
+        "//lib:args4j",
+        "//lib:guava",
+        "//lib:gwtorm",
+        "//lib/jgit/org.eclipse.jgit:jgit",
+    ],
+)
diff --git a/java/com/google/gerrit/pgm/ProtoGen.java b/java/com/google/gerrit/proto/ProtoGen.java
similarity index 67%
rename from java/com/google/gerrit/pgm/ProtoGen.java
rename to java/com/google/gerrit/proto/ProtoGen.java
index a882412..1c55a05 100644
--- a/java/com/google/gerrit/pgm/ProtoGen.java
+++ b/java/com/google/gerrit/proto/ProtoGen.java
@@ -12,11 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package com.google.gerrit.pgm;
+package com.google.gerrit.proto;
 
+import static com.google.common.base.Preconditions.checkState;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import com.google.gerrit.pgm.util.AbstractProgram;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gwtorm.schema.java.JavaSchemaModel;
 import java.io.BufferedWriter;
@@ -28,23 +28,37 @@
 import java.nio.ByteBuffer;
 import org.eclipse.jgit.internal.storage.file.LockFile;
 import org.eclipse.jgit.util.IO;
+import org.kohsuke.args4j.CmdLineException;
+import org.kohsuke.args4j.CmdLineParser;
 import org.kohsuke.args4j.Option;
 
-public class ProtoGen extends AbstractProgram {
+public class ProtoGen {
   @Option(
-      name = "--output",
-      aliases = {"-o"},
-      required = true,
-      metaVar = "FILE",
-      usage = "File to write .proto into")
+    name = "--output",
+    aliases = {"-o"},
+    required = true,
+    metaVar = "FILE",
+    usage = "File to write .proto into"
+  )
   private File file;
 
-  @Override
-  public int run() throws Exception {
-    LockFile lock = new LockFile(file.getAbsoluteFile());
-    if (!lock.lock()) {
-      throw die("Cannot lock " + file);
+  public static void main(String[] argv) throws Exception {
+    System.exit(new ProtoGen().run(argv));
+  }
+
+  private int run(String[] argv) throws Exception {
+    CmdLineParser parser = new CmdLineParser(this);
+    try {
+      parser.parseArgument(argv);
+    } catch (CmdLineException e) {
+      System.err.println(e.getMessage());
+      System.err.println(getClass().getSimpleName() + " -o output.proto");
+      parser.printUsage(System.err);
+      return 1;
     }
+
+    LockFile lock = new LockFile(file.getAbsoluteFile());
+    checkState(lock.lock(), "cannot lock %s", file);
     try {
       JavaSchemaModel jsm = new JavaSchemaModel(ReviewDb.class);
       try (OutputStream o = lock.getOutputStream();
@@ -61,9 +75,7 @@
         jsm.generateProto(out);
         out.flush();
       }
-      if (!lock.commit()) {
-        throw die("Could not write to " + file);
-      }
+      checkState(lock.commit(), "Could not write to %s", file);
     } finally {
       lock.unlock();
     }
diff --git a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
index 6879ec6..3c5585c 100644
--- a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
+++ b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
@@ -38,6 +38,7 @@
 import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_MISSING_OBJECT;
 import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_REASON;
 
+import com.google.auto.value.AutoValue;
 import com.google.common.base.Function;
 import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
@@ -370,7 +371,15 @@
   private final ListMultimap<ReceiveError, String> errors;
   private final ListMultimap<String, String> pushOptions;
   private final Map<Change.Id, ReplaceRequest> replaceByChange;
-  private final Set<ObjectId> validCommits;
+
+  @AutoValue
+  protected abstract static class ValidCommitKey {
+    abstract ObjectId getObjectId();
+
+    abstract Branch.NameKey getBranch();
+  }
+
+  private final Set<ValidCommitKey> validCommits;
 
   /**
    * Actual commands to be executed, as opposed to the mix of actual and magic commands that were
@@ -1893,13 +1902,7 @@
           logDebug("Creating new change for %s even though it is already tracked", name);
         }
 
-        if (!validCommit(
-            receivePack.getRevWalk(),
-            magicBranch.perm,
-            magicBranch.dest,
-            magicBranch.cmd,
-            c,
-            null)) {
+        if (!validCommit(receivePack.getRevWalk(), magicBranch.dest, magicBranch.cmd, c, null)) {
           // Not a change the user can propose? Abort as early as possible.
           logDebug("Aborting early due to invalid commit");
           return Collections.emptyList();
@@ -2486,9 +2489,8 @@
         }
       }
 
-      PermissionBackend.ForRef perm = permissions.ref(change.getDest().get());
       if (!validCommit(
-          receivePack.getRevWalk(), perm, change.getDest(), inputCommand, newCommit, change)) {
+          receivePack.getRevWalk(), change.getDest(), inputCommand, newCommit, change)) {
         return false;
       }
       receivePack.getRevWalk().parseBody(priorCommit);
@@ -2860,7 +2862,7 @@
         }
         if (existing.keySet().contains(c)) {
           continue;
-        } else if (!validCommit(walk, perm, branch, cmd, c, null)) {
+        } else if (!validCommit(walk, branch, cmd, c, null)) {
           break;
         }
 
@@ -2878,15 +2880,12 @@
   }
 
   private boolean validCommit(
-      RevWalk rw,
-      PermissionBackend.ForRef perm,
-      Branch.NameKey branch,
-      ReceiveCommand cmd,
-      ObjectId id,
-      @Nullable Change change)
+      RevWalk rw, Branch.NameKey branch, ReceiveCommand cmd, ObjectId id, @Nullable Change change)
       throws IOException {
+    PermissionBackend.ForRef perm = permissions.ref(branch.get());
 
-    if (validCommits.contains(id)) {
+    ValidCommitKey key = new AutoValue_ReceiveCommits_ValidCommitKey(id.copy(), branch);
+    if (validCommits.contains(key)) {
       return true;
     }
 
@@ -2912,7 +2911,7 @@
       reject(cmd, e.getMessage());
       return false;
     }
-    validCommits.add(c.copy());
+    validCommits.add(key);
     return true;
   }
 
diff --git a/java/com/google/gerrit/server/submit/SubmoduleOp.java b/java/com/google/gerrit/server/submit/SubmoduleOp.java
index 0ed189e..319e2e1 100644
--- a/java/com/google/gerrit/server/submit/SubmoduleOp.java
+++ b/java/com/google/gerrit/server/submit/SubmoduleOp.java
@@ -516,13 +516,26 @@
                 + "doesn't have gitlink file mode.";
         throw new SubmoduleException(errMsg);
       }
+      // Parse the current gitlink entry commit in the subproject repo. This is used to add a
+      // shortlog for this submodule to the commit message in the superproject.
+      //
+      // Even if we don't strictly speaking need that commit message, parsing the commit is a sanity
+      // check that the old gitlink is a commit that actually exists. If not, then there is an
+      // inconsistency between the superproject and subproject state, and we don't want to risk
+      // making things worse by updating the gitlink to something else.
       oldCommit = subOr.rw.parseCommit(dce.getObjectId());
     }
 
     final CodeReviewCommit newCommit;
     if (branchTips.containsKey(s.getSubmodule())) {
+      // This submodule's branch was updated as part of this specific submit batch: update the
+      // gitlink to point to the new commit from the batch.
       newCommit = branchTips.get(s.getSubmodule());
     } else {
+      // For whatever reason, this submodule was not updated as part of this submit batch, but the
+      // superproject is still subscribed to this branch. Re-read the ref to see if anything has
+      // changed since the last time the gitlink was updated, and roll that update into the same
+      // commit as all other submodule updates.
       Ref ref = subOr.repo.getRefDatabase().exactRef(s.getSubmodule().get());
       if (ref == null) {
         ed.add(new DeletePath(s.getPath()));
diff --git a/javatests/com/google/gerrit/proto/BUILD b/javatests/com/google/gerrit/proto/BUILD
new file mode 100644
index 0000000..0940f6b
--- /dev/null
+++ b/javatests/com/google/gerrit/proto/BUILD
@@ -0,0 +1,17 @@
+load("//tools/bzl:junit.bzl", "junit_tests")
+
+junit_tests(
+    name = "proto_tests",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//lib/truth:truth-proto-extension",
+        "//proto:reviewdb_java_proto",
+
+        # TODO(dborowitz): These are already runtime_deps of
+        # truth-proto-extension, but either omitting them or adding them as
+        # runtime_deps to this target fails with:
+        #   class file for com.google.common.collect.Multimap not found
+        "//lib:guava",
+        "//lib/truth",
+    ],
+)
diff --git a/javatests/com/google/gerrit/proto/ReviewDbProtoTest.java b/javatests/com/google/gerrit/proto/ReviewDbProtoTest.java
new file mode 100644
index 0000000..49cd2921
--- /dev/null
+++ b/javatests/com/google/gerrit/proto/ReviewDbProtoTest.java
@@ -0,0 +1,31 @@
+// Copyright (C) 2018 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.proto;
+
+import static com.google.common.truth.extensions.proto.ProtoTruth.assertThat;
+
+import com.google.gerrit.proto.reviewdb.Reviewdb.Change;
+import com.google.gerrit.proto.reviewdb.Reviewdb.Change_Id;
+import org.junit.Test;
+
+public class ReviewDbProtoTest {
+  @Test
+  public void generatedProtoApi() {
+    Change c1 = Change.newBuilder().setChangeId(Change_Id.newBuilder().setId(1234).build()).build();
+    Change c2 = Change.newBuilder().setChangeId(Change_Id.newBuilder().setId(5678).build()).build();
+    assertThat(c1).isEqualTo(c1);
+    assertThat(c1).isNotEqualTo(c2);
+  }
+}
diff --git a/lib/BUILD b/lib/BUILD
index a9d82e9..38b0b80 100644
--- a/lib/BUILD
+++ b/lib/BUILD
@@ -72,7 +72,11 @@
     name = "gwtorm",
     visibility = ["//visibility:public"],
     exports = [":gwtorm-client"],
-    runtime_deps = [":protobuf"],
+    runtime_deps = [
+        ":protobuf",
+        "//lib/antlr:java-runtime",
+        "//lib/ow2:ow2-asm",
+    ],
 )
 
 java_library(
diff --git a/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html b/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html
index 89f3038..60eaf1f 100644
--- a/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html
+++ b/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.html
@@ -48,7 +48,9 @@
     shouldSuppressKeyboardShortcut(e) {
       e = getKeyboardEvent(e);
       const tagName = Polymer.dom(e).rootTarget.tagName;
-      if (tagName === 'INPUT' || tagName === 'TEXTAREA') {
+      if (tagName === 'INPUT' || tagName === 'TEXTAREA' ||
+          (e.keyCode === 13 && tagName === 'A')) {
+        // Suppress shortcuts if the key is 'enter' and target is an anchor.
         return true;
       }
       for (let i = 0; e.path && i < e.path.length; i++) {
diff --git a/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior_test.html b/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior_test.html
index 8e10302..04193dd 100644
--- a/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior_test.html
+++ b/polygerrit-ui/app/behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior_test.html
@@ -51,6 +51,7 @@
         behaviors: [Gerrit.KeyboardShortcutBehavior],
         keyBindings: {
           k: '_handleKey',
+          enter: '_handleKey',
         },
         _handleKey() {},
       });
@@ -107,6 +108,17 @@
       MockInteractions.keyDownOn(divEl, 75, null, 'k');
     });
 
+    test('blocks enter shortcut on an anchor', done => {
+      const anchorEl = document.createElement('a');
+      const element = overlay.querySelector('test-element');
+      element.appendChild(anchorEl);
+      element._handleKey = e => {
+        assert.isTrue(element.shouldSuppressKeyboardShortcut(e));
+        done();
+      };
+      MockInteractions.keyDownOn(anchorEl, 13, null, 'enter');
+    });
+
     test('modifierPressed returns accurate values', () => {
       const spy = sandbox.spy(element, 'modifierPressed');
       element._handleKey = e => {
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
index edf9f5a..90d465f 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment.js
@@ -449,6 +449,13 @@
       this.fire('comment-discard', this._getEventPayload());
     },
 
+    _handleFix() {
+      this.dispatchEvent(new CustomEvent('create-fix-comment', {
+        bubbles: true,
+        detail: this._getEventPayload(),
+      }));
+    },
+
     _handleDiscard(e) {
       e.preventDefault();
       this.$.reporting.recordDraftInteraction();
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
index f1ac649..ca85892 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-comment/gr-diff-comment_test.html
@@ -841,5 +841,16 @@
       element.save();
       assert.isTrue(discardStub.called);
     });
+
+    test('_handleFix fires create-fix event', done => {
+      element.addEventListener('create-fix-comment', e => {
+        assert.deepEqual(e.detail, element._getEventPayload());
+        done();
+      });
+      element.isRobotComment = true;
+      flushAsynchronousOperations();
+
+      MockInteractions.tap(element.$$('.fix'));
+    });
   });
 </script>
diff --git a/proto/BUILD b/proto/BUILD
index 4528dcb..0578ca5 100644
--- a/proto/BUILD
+++ b/proto/BUILD
@@ -8,3 +8,21 @@
     visibility = ["//visibility:public"],
     deps = [":cache_proto"],
 )
+
+genrule(
+    name = "gen_reviewdb_proto",
+    outs = ["reviewdb.proto"],
+    cmd = "$(location //java/com/google/gerrit/proto:ProtoGen) -o $@",
+    tools = ["//java/com/google/gerrit/proto:ProtoGen"],
+)
+
+proto_library(
+    name = "reviewdb_proto",
+    srcs = [":reviewdb.proto"],
+)
+
+java_proto_library(
+    name = "reviewdb_java_proto",
+    visibility = ["//javatests/com/google/gerrit/proto:__pkg__"],
+    deps = [":reviewdb_proto"],
+)
diff --git a/resources/com/google/gerrit/proto/BUILD b/resources/com/google/gerrit/proto/BUILD
new file mode 100644
index 0000000..ec2e05c
--- /dev/null
+++ b/resources/com/google/gerrit/proto/BUILD
@@ -0,0 +1,8 @@
+filegroup(
+    name = "proto",
+    srcs = glob(
+        ["**/*"],
+        exclude = ["BUILD"],
+    ),
+    visibility = ["//visibility:public"],
+)
diff --git a/resources/com/google/gerrit/pgm/ProtoGenHeader.txt b/resources/com/google/gerrit/proto/ProtoGenHeader.txt
similarity index 95%
rename from resources/com/google/gerrit/pgm/ProtoGenHeader.txt
rename to resources/com/google/gerrit/proto/ProtoGenHeader.txt
index a380955..8797790 100644
--- a/resources/com/google/gerrit/pgm/ProtoGenHeader.txt
+++ b/resources/com/google/gerrit/proto/ProtoGenHeader.txt
@@ -14,7 +14,6 @@
 
 syntax = "proto2";
 
-option java_api_version = 2;
 option java_package = "com.google.gerrit.proto.reviewdb";
 
 package devtools.gerritcodereview;