Upgrade JGit to 4.1.0.201509280440-r

Includes Jacob Keller's fix to show submodule differences properly[1].
See the full release notes[2] for further details.

v2.12-rc0~528^2 (Use exactRef() when possible, 2015-06-20) changed the
expectation in ListBranchesIt#listBranchesOfEmptyProject to work
around a bug in exactRef where it would treat a symref pointing to an
unknown branch as missing.  That bug has been fixed in both ref
database backends in JGit:

  in DfsRepository, d0e47a99 (2015-07-16)
  in FileRepository, 797f94d3 (2015-11-11)

(more details at https://bugs.eclipse.org/478865).  So add HEAD back
to the expected list of branches.

[1] https://git.eclipse.org/r/#/c/56263/
[2] https://projects.eclipse.org/projects/technology.jgit/releases/4.1.0

Change-Id: I97f3be172de8cdd8ecf6a3eacb037d4a6332b50f

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/rest/project/ListBranchesIT.java

@@ -47,6 +47,7 @@ public class ListBranchesIT extends AbstractDaemonTest {
   @TestProjectInput(createEmptyCommit = false)
   public void listBranchesOfEmptyProject() throws Exception {
     assertBranches(ImmutableList.of(
+          branch("HEAD", null, false),
           branch("refs/meta/config",  null, false)),
         list().get());
   }

lib/jgit/BUCK

@@ -1,13 +1,13 @@
 include_defs('//lib/maven.defs')
 
-REPO = GERRIT # Leave here even if set to MAVEN_CENTRAL.
+REPO = MAVEN_CENTRAL # Leave here even if set to MAVEN_CENTRAL.
-VERS = '4.0.1.201506240215-r.94-g39dc898'
+VERS = '4.1.0.201509280440-r'
 
 maven_jar(
   name = 'jgit',
   id = 'org.eclipse.jgit:org.eclipse.jgit:' + VERS,
-  bin_sha1 = 'e076b3f71daaadd27e9cfc810778968deed04038',
+  bin_sha1 = '6410f290b796184df95d321a18d4c3665ba542a8',
-  src_sha1 = '255a8c836c1a85da9ffc371ba3e59e63c2bc1dee',
+  src_sha1 = 'a681c59ec854b3e55f3abff8442e3e4ece31fa70',
   license = 'jgit',
   repository = REPO,
   unsign = True,
@@ -22,7 +22,7 @@ maven_jar(
 maven_jar(
   name = 'jgit-servlet',
   id = 'org.eclipse.jgit:org.eclipse.jgit.http.server:' + VERS,
-  sha1 = '4d4346164f89593a82670780fd041be358ab76c9',
+  sha1 = '2f86ccebd5b5e0837757d35f63f04471432c13b8',
   license = 'jgit',
   repository = REPO,
   deps = [':jgit'],
@@ -36,7 +36,7 @@ maven_jar(
 maven_jar(
   name = 'jgit-archive',
   id = 'org.eclipse.jgit:org.eclipse.jgit.archive:' + VERS,
-  sha1 = '96408a19e7506bf19f25b55574ca212a3e789961',
+  sha1 = 'd6d0ec8d77cea3b7efeac9789140f8373c10454b',
   license = 'jgit',
   repository = REPO,
   deps = [':jgit',
@@ -53,7 +53,7 @@ maven_jar(
 maven_jar(
   name = 'junit',
   id = 'org.eclipse.jgit:org.eclipse.jgit.junit:' + VERS,
-  sha1 = '172e9b034bdd85b9611f3958258733fd74889cc7',
+  sha1 = '69ef53175d9f150bc4072f8f5ba9046bf14cc55f',
   license = 'DO_NOT_DISTRIBUTE',
   repository = REPO,
   unsign = True,