Make release script cleanup more robust.

tools/push-to-trunk/common_includes.py

 #!/usr/bin/env python
 # Copyright 2013 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
@@ skipping 588 matching lines @@
     self["current_branch"] = self.GitCurrentBranch()
 
     # Fetch unfetched revisions.
     self.vc.Fetch()
 
   def PrepareBranch(self):
     # Delete the branch that will be created later if it exists already.
     self.DeleteBranch(self._config["BRANCHNAME"])
 
   def CommonCleanup(self):
-    self.GitCheckout(self["current_branch"])
+    if ' ' in self["current_branch"]:
+      self.GitCheckout('master')
+    else:
+      self.GitCheckout(self["current_branch"])
     if self._config["BRANCHNAME"] != self["current_branch"]:
       self.GitDeleteBranch(self._config["BRANCHNAME"])
 
     # Clean up all temporary files.
     for f in glob.iglob("%s*" % self._config["PERSISTFILE_BASENAME"]):
       if os.path.isfile(f):
         os.remove(f)
       if os.path.isdir(f):
         shutil.rmtree(f)
 
@@ skipping 260 matching lines @@
     for (number, step_class) in enumerate(step_classes):
       steps.append(MakeStep(step_class, number, self._state, self._config,
                             options, self._side_effect_handler))
     for step in steps[options.step:]:
       if step.Run():
         return 0
     return 0
 
   def Run(self, args=None):
     return self.RunSteps(self._Steps(), args)