Make release script cleanup more robust.

This is a work-around that checks out master if the
remembered branch is corrupt.

BUG=chromium:410721
LOG=n
TEST=script_test.py
TBR=tandrii@chromium.org

Review URL: https://codereview.chromium.org/659473002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24599 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

tools/push-to-trunk/common_includes.py

@@ -606,7 +606,10 @@ class Step(GitRecipesMixin):
     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"])