Fix resolution of local branch name in scm and rebaseline tools.

Tools/Scripts/webkitpy/common/checkout/scm/git.py

Index: Tools/Scripts/webkitpy/common/checkout/scm/git.py
diff --git a/Tools/Scripts/webkitpy/common/checkout/scm/git.py b/Tools/Scripts/webkitpy/common/checkout/scm/git.py
index 9a73ce961aef45e36770c1f1e125ce49c5076e0e..2423c565708e73920e46d685a87d696d8bdeb6a6 100644
--- a/Tools/Scripts/webkitpy/common/checkout/scm/git.py
+++ b/Tools/Scripts/webkitpy/common/checkout/scm/git.py
@@ -134,7 +134,9 @@ class Git(SCM):
         return ref.replace('refs/heads/', '')
 
     def current_branch(self):
-        return self._branch_from_ref(self._run_git(['symbolic-ref', '-q', 'HEAD']).strip())
+        # Returns an empty string if HEAD is detached.

[Xianzhu, 2015/07/16 22:01:19]

The following code will return 'HEAD' when HEAD is detached, right?

[joelo, 2015/07/16 23:00:11]

Whoops, you're right. I meant to check for that and convert it to an empty
string.

+        ref = self._run_git(['rev-parse', '--symbolic-full-name', 'HEAD']).strip()
+        return self._branch_from_ref(ref)
 
     def _upstream_branch(self):
         current_branch = self.current_branch()