cbuildbot: Add api version to --git-cache-dir.

Also, use the same version for the deprecated --repo-cache option.

BUG=chromium:650713
TEST=run_tests

Change-Id: I03c4636b87f93fe786079f59c7200bf22383e5c4
Reviewed-on: https://chromium-review.googlesource.com/389873
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
diff --git a/scripts/cbuildbot.py b/scripts/cbuildbot.py
index 0ece3d1..4cde5a6 100644
--- a/scripts/cbuildbot.py
+++ b/scripts/cbuildbot.py
@@ -523,7 +523,8 @@
   parser.add_remote_option('--repo-cache', type='path',
                            help='Directory from which to copy a repo checkout '
                                 'if our build root is empty, to avoid '
-                                'excessive GoB load with a fresh sync.')
+                                'excessive GoB load with a fresh sync.'
+                                'Deprecated in favor of --git-cache-dir.')
   group.add_remote_option('--no-buildbot-tags', action='store_false',
                           dest='enable_buildbot_tags', default=True,
                           help='Suppress buildbot specific tags from log '
@@ -624,6 +625,7 @@
                                 'version rather than create or get latest. '
                                 'Examples: 4815.0.0-rc1, 4815.1.2'))
   group.add_remote_option('--git-cache-dir', dest='git_cache_dir', default=None,
+                          api=constants.REEXEC_API_GIT_CACHE_DIR,
                           help=('Specify the cache directory to store the '
                                 'project caches populated by the git-cache '
                                 'tool. Bootstrap the projects based on the git '