Assume 'master' when remote branch not specified.

apply_issue.py

Index: apply_issue.py
diff --git a/apply_issue.py b/apply_issue.py
index 690db0d323e4f545af0544288846548b0bb396a3..3d235ea91a687abb87956e3bce1fd2d928ef26f6 100755
--- a/apply_issue.py
+++ b/apply_issue.py
@@ -161,8 +161,13 @@ def main():
   if scm_type == 'svn':
     scm_obj = checkout.SvnCheckout(full_dir, None, None, None, None)
   elif scm_type == 'git':
-    scm_obj = checkout.GitCheckout(full_dir, None, None, None, None,
-                                   base_ref=options.base_ref,)
+    scm_obj = checkout.GitCheckout(root_dir=full_dir,
+                                   project_name=None,
+                                   remote_branch='master',
+                                   git_url=None,
+                                   commit_user=None,
+                                   base_ref=options.base_ref,
+                                   post_processors=None)
   elif scm_type == None:
     scm_obj = checkout.RawCheckout(full_dir, None, None)
   else: