Fix gclient branch ref mangling and allow --force branch switches.

tests/gclient_scm_test.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unit tests for gclient_scm.py."""
 
 # pylint: disable=E1103
 
 # Import before super_mox to keep valid references.
@@ skipping 1543 matching lines @@
     scm.update(options, (), file_list)
 
     self.assertEquals(file_list, expected_file_list)
     self.assertEquals(scm.revinfo(options, (), None),
                       '9a51244740b25fa2ded5252ca00a3178d3f665a9')
     self.assertEquals(self.getCurrentBranch(), 'feature')
     self.checkNotInStdout('Checked out feature to a detached HEAD')
 
     rmtree(origin_root_dir)
 
-  def testUpdateCloneOnDetachedBranch(self):
+  def testUpdateCloneOnFetchedRemoteBranch(self):
     if not self.enabled:
       return
     options = self.Options()
 
     origin_root_dir = self.root_dir
     self.root_dir = tempfile.mkdtemp()
     self.relpath = '.'
     self.base_path = join(self.root_dir, self.relpath)
     url_with_branch_ref = origin_root_dir + '@refs/remotes/origin/feature'
 
@@ skipping 11 matching lines @@
     self.assertEquals(file_list, expected_file_list)
     self.assertEquals(scm.revinfo(options, (), None),
                       '9a51244740b25fa2ded5252ca00a3178d3f665a9')
     # indicates detached HEAD
     self.assertEquals(self.getCurrentBranch(), None)
     self.checkInStdout(
       'Checked out refs/remotes/origin/feature to a detached HEAD')
 
     rmtree(origin_root_dir)
 
-  def testUpdateCloneOnBranchHead(self):
+  def testUpdateCloneOnTrueRemoteBranch(self):
     if not self.enabled:
       return
     options = self.Options()
 
     origin_root_dir = self.root_dir
     self.root_dir = tempfile.mkdtemp()
     self.relpath = '.'
     self.base_path = join(self.root_dir, self.relpath)
     url_with_branch_ref = origin_root_dir + '@refs/heads/feature'
 
     scm = gclient_scm.CreateSCM(url=url_with_branch_ref,
                                 root_dir=self.root_dir,
                                 relpath=self.relpath)
 
     expected_file_list = [join(self.base_path, "a"),
                           join(self.base_path, "b"),
                           join(self.base_path, "c")]
     file_list = []
     options.revision = 'unmanaged'
     scm.update(options, (), file_list)
 
     self.assertEquals(file_list, expected_file_list)
     self.assertEquals(scm.revinfo(options, (), None),
                       '9a51244740b25fa2ded5252ca00a3178d3f665a9')
-    self.assertEquals(self.getCurrentBranch(), 'feature')
-    self.checkNotInStdout(
-      'Checked out refs/heads/feature to a detached HEAD')
+    # @refs/heads/feature is AKA @refs/remotes/origin/feature in the clone, so
+    # should be treated as such by gclient.
+    # TODO(mmoss): Though really, we should only allow DEPS to specify branches
+    # as they are known in the upstream repo, since the mapping into the local
+    # repo can be modified by users (or we might even want to change the gclient
+    # defaults at some point). But that will take more work to stop using
+    # refs/remotes/ everywhere that we do (and to stop assuming a DEPS ref will
+    # always resolve locally, like when passing them to show-ref or rev-list).
+    self.assertEquals(self.getCurrentBranch(), None)
+    self.checkInStdout(
+      'Checked out refs/remotes/origin/feature to a detached HEAD')
 
     rmtree(origin_root_dir)
 
   def testUpdateUpdate(self):
     if not self.enabled:
       return
     options = self.Options()
     expected_file_list = []
     scm = gclient_scm.CreateSCM(url=self.url, root_dir=self.root_dir,
                                 relpath=self.relpath)
     file_list = []
     options.revision = 'unmanaged'
     scm.update(options, (), file_list)
     self.assertEquals(file_list, expected_file_list)
     self.assertEquals(scm.revinfo(options, (), None),
                       '069c602044c5388d2d15c3f875b057c852003458')
     self.checkstdout('________ unmanaged solution; skipping .\n')
 
 
 if __name__ == '__main__':
   level = logging.DEBUG if '-v' in sys.argv else logging.FATAL
   logging.basicConfig(
       level=level,
       format='%(asctime).19s %(levelname)s %(filename)s:'
              '%(lineno)s %(message)s')
   unittest.main()
 
 # vim: ts=2:sw=2:tw=80:et: