DeleteRef: Do not return 409 Conflict if an error occurred

If an error occurs the response should be 500 Internal Server Error.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I007f61fd47d4c4a70edda5af0d78e1a176730f03
(cherry picked from commit ee512f136cfc8b4adf246f6ef563e3b984b4fb2d)

java/com/google/gerrit/server/restapi/project/DeleteRef.java

diff --git a/java/com/google/gerrit/server/restapi/project/DeleteRef.java b/java/com/google/gerrit/server/restapi/project/DeleteRef.java
index 1e79e9c..dae759a 100644
--- a/java/com/google/gerrit/server/restapi/project/DeleteRef.java
+++ b/java/com/google/gerrit/server/restapi/project/DeleteRef.java
@@ -25,6 +25,7 @@
 import com.google.common.collect.Iterables;
 import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.common.Nullable;
+import com.google.gerrit.exceptions.StorageException;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
 import com.google.gerrit.reviewdb.client.Branch;
@@ -167,8 +168,7 @@
         case REJECTED_MISSING_OBJECT:
         case REJECTED_OTHER_REASON:
         default:
-          logger.atSevere().log("Cannot delete %s: %s", ref, result.name());
-          throw new ResourceConflictException("cannot delete: " + result.name());
+          throw new StorageException(String.format("Cannot delete %s: %s", ref, result.name()));
       }
     }
   }