Include branch name in git-squash-branch's default message

Change-Id: I5dfa6017d1c938f8e1c55fbd6e607909aa4d6811
Reviewed-on: https://chromium-review.googlesource.com/422589
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Alan Cutter <alancutter@chromium.org>

git_common.py

@@ -810,7 +810,7 @@ def status():
 
 
 def squash_current_branch(header=None, merge_base=None):
-  header = header or 'git squash commit.'
+  header = header or 'git squash commit for %s.' % current_branch()
   merge_base = merge_base or get_or_create_merge_base(current_branch())
   log_msg = header + '\n'
   if log_msg:

git_squash_branch.py

@@ -11,7 +11,7 @@ import git_common
 def main(args):
   parser = argparse.ArgumentParser()
   parser.add_argument(
-      '-m', '--message', metavar='<msg>', default='git squash commit.',
+      '-m', '--message', metavar='<msg>', default=None,
       help='Use the given <msg> as the first line of the commit message.')
   opts = parser.parse_args(args)
   if git_common.is_dirty_git_tree('squash-branch'):

man/src/git-squash-branch.txt

@@ -35,7 +35,7 @@ OPTIONS
 -m <message>::
 --message=<message>::
   Optional message to use for the first line of the squashed commit. If omitted,
-  it defaults to "git squash commit.".
+  it defaults to "git squash commit for <branch>.".
 
 EXAMPLE
 -------

tests/git_common_test.py

@@ -681,6 +681,12 @@ class GitMutableStructuredTest(git_test_utils.GitRepoReadWriteTestBase,
       'K'
     )
 
+  def testSquashBranchDefaultMessage(self):
+    self.repo.git('checkout', 'branch_K')
+    self.assertEquals(True, self.repo.run(self.gc.squash_current_branch))
+    self.assertEquals(self.repo.run(self.gc.run, 'log', '-n1', '--format=%s'),
+                      'git squash commit for branch_K.')
+
   def testSquashBranchEmpty(self):
     self.repo.git('checkout', 'branch_K')
     self.repo.git('checkout', 'branch_G', '.')