RFR: 1235: git sync --branches doesn't work as expected

[Zhao Song]

Make git sync --branches works as expected.

The argument after git sync --branches will not be ignored right now.

-------------

Commit messages:
 - fix the bug on 'git sync --branches'

Changes: https://git.openjdk.org/skara/pull/1381/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1381&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1235
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/skara/pull/1381.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1381/head:pull/1381

PR: https://git.openjdk.org/skara/pull/1381