This commit allows users to omit `--branch` from command line options.
`repo_pull.py` will not call `repo start` if `--branch` is unspecified.
Test: repo_pull.py bash -g GERRIT QUERY
Change-Id: I62380485f057bd35ab8ae4d5e70372ff5d05fcc5
This commit adds `-m checkout` for merge commits. If `-m checkout` is
specified, `repo_pull.py` will pull the merge commits with
`git checkout FETCH_HEAD`.
Test: repo_pull.py bash -g GERRIT QUERY -m checkout -b local_branch_name
Change-Id: I6cbedbd2941c63c8bb0591b6033a136829ffda47
With `repo_pull.py`, users can specify a query string and pull all
matching change lists from Gerrit.
Test: repo_pull.py pull -g GERRIT QUERY
Change-Id: I1c64c9d630ab37f94276fde7a654f322ac3aa43c
