Fix broken tar.xz archive download

Gitiles advertises the tar.xz archive format (ArchiveFormat.TXZ), but
the generated gitiles.war did not package org.tukaani.xz. JGit's Bazel
jgit-archive target failed to declare it (the //lib:xz target was
testonly), so it was never pulled transitively. Requesting a .tar.xz
archive therefore failed at runtime with NoClassDefFoundError:
org/tukaani/xz/..., and no test caught it because the only archive test
exercised tar.gz.

Bump the JGit submodule to pick up the fix that declares org.tukaani.xz
as a dependency of the archive library, and add a regression test that
streams a .tar.xz archive.

Depends-On: https://eclipse.gerrithub.io/c/eclipse-jgit/jgit/+/1247298
Change-Id: I1cd020dc4c4d0e3059d7f3b57ac2771f6037c50d

javatests/com/google/gitiles/ArchiveServletTest.java

diff --git a/javatests/com/google/gitiles/ArchiveServletTest.java b/javatests/com/google/gitiles/ArchiveServletTest.java
index 8d7bc4c..e5e8c08 100644
--- a/javatests/com/google/gitiles/ArchiveServletTest.java
+++ b/javatests/com/google/gitiles/ArchiveServletTest.java
@@ -55,4 +55,24 @@
     byte[] body = res.getActualBody();
     assertThat(body.length).isGreaterThan(20);
   }
+
+  @Test
+  public void tarXzArchive_regressionForMissingXzDependency() throws Exception {
+    repo.branch("master").commit().add("README.md", "hello\n").create();
+
+    FakeHttpServletResponse res =
+        buildResponse("/repo/+archive/refs/heads/master.tar.xz", /* queryString= */ null, SC_OK);
+
+    String contentType = res.getHeader(HttpHeaders.CONTENT_TYPE);
+    assertThat(contentType).isNotNull();
+    assertThat(contentType.toLowerCase()).contains("xz");
+
+    String cd = res.getHeader(HttpHeaders.CONTENT_DISPOSITION);
+    assertThat(cd).isNotNull();
+    assertThat(cd).contains("attachment");
+    assertThat(cd).contains(".tar.xz");
+
+    byte[] body = res.getActualBody();
+    assertThat(body.length).isGreaterThan(20);
+  }
 }

modules/jgit

diff --git a/modules/jgit b/modules/jgit
index fe01de6..2bf2e4a 160000
--- a/modules/jgit
+++ b/modules/jgit
@@ -1 +1 @@
-Subproject commit fe01de69f44611049b664188652bf9e340f0b1f8
+Subproject commit 2bf2e4a32ef9347617a73ae739d08fc48c029989