repo-pull: Introduce --current-branch argument

To make the script can be used from automatic scripts, introduce
`--current-branch` argument which allows pulling commits to the current
branch without creating a local branch. It will skip the prompt which
asking about the creation of a local branch.

Test: With --current-branch argument, the script doesn't ask setting
  local branch name.
Change-Id: Iff3cdebe6338bb2be738e60047d5c4dd81cde4f0
Signed-off-by: Junghoon Jang <junghoonjang@google.com>
diff --git a/tools/repo_pull/repo_pull.py b/tools/repo_pull/repo_pull.py
index 3491eb9..b4bdfea 100755
--- a/tools/repo_pull/repo_pull.py
+++ b/tools/repo_pull/repo_pull.py
@@ -409,6 +409,9 @@
     parser.add_argument('-j', '--parallel', default=1, type=int,
                         help='Number of parallel running commands')
 
+    parser.add_argument('--current-branch', action='store_true',
+                        help='Pull commits to the current branch')
+
     return parser.parse_args()
 
 
@@ -421,7 +424,7 @@
 
 def _get_local_branch_name_from_args(args):
     """Get the local branch name from args."""
-    if not args.branch and not _confirm(
+    if not args.branch and not args.current_branch and not _confirm(
             'Do you want to continue without local branch name?', False):
         print('error: `-b` or `--branch` must be specified', file=sys.stderr)
         sys.exit(1)