Add --merge option to gclient sync.

BUG=none
TEST=

Review URL: http://codereview.chromium.org/7277035

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@93611 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/gclient.py b/gclient.py
index 4cc4186..93bc8b4 100644
--- a/gclient.py
+++ b/gclient.py
@@ -1090,6 +1090,9 @@
                          'local modifications')
   parser.add_option('-R', '--reset', action='store_true',
                     help='resets any local changes before updating (git only)')
+  parser.add_option('-M', '--merge', action='store_true',
+                    help='merge upstream changes instead of trying to '
+                         'fast-forward or rebase')
   parser.add_option('--deps', dest='deps_os', metavar='OS_LIST',
                     help='override deps for the specified (comma-separated) '
                          'platform(s); \'all\' will process all deps_os '