manifest_version: use CrOS-Build-Id label to annotate commit messages

BUG=chromium:398267
TEST=Unit tests

Change-Id: Ic0f37ae2623fe3f3b8d1c8cda47658ffedf2eb51
Reviewed-on: https://chromium-review.googlesource.com/211960
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
diff --git a/cbuildbot/manifest_version.py b/cbuildbot/manifest_version.py
index 3cb4e34..be47e9a 100644
--- a/cbuildbot/manifest_version.py
+++ b/cbuildbot/manifest_version.py
@@ -574,7 +574,7 @@
     commit_message = 'Automatic: Start %s %s %s' % (self.build_names[0],
                                                     self.branch, version)
     if build_id is not None and build_id >= 0:
-      commit_message += '\nbuild_id: %s' % build_id
+      commit_message += '\nCrOS-Build-Id: %s' % build_id
 
     logging.info('Publishing build spec for: %s', version)
     logging.info('Publishing with commit message: %s', commit_message)
diff --git a/cbuildbot/manifest_version_unittest.py b/cbuildbot/manifest_version_unittest.py
index fbc6f44..9ac0962 100755
--- a/cbuildbot/manifest_version_unittest.py
+++ b/cbuildbot/manifest_version_unittest.py
@@ -178,7 +178,7 @@
   def testPublishManifestCommitMessageWithBuildId(self):
     """Tests that PublishManifest writes a build id."""
     expected_message = ('Automatic: Start x86-generic-paladin master 1\n'
-                        'build_id: %s' % MOCK_BUILD_ID)
+                        'CrOS-Build-Id: %s' % MOCK_BUILD_ID)
     self.mox.StubOutWithMock(self.manager, 'PushSpecChanges')
 
     info = manifest_version.VersionInfo(