Fix git interface for merge script.

tools/push-to-trunk/test_scripts.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 1185 matching lines @@
       self.assertTrue(re.search(r"#define MINOR_VERSION\s+22", version))
       self.assertTrue(re.search(r"#define BUILD_NUMBER\s+5", version))
       self.assertTrue(re.search(r"#define PATCH_LEVEL\s+1", version))
       self.assertTrue(re.search(r"#define IS_CANDIDATE_VERSION\s+0", version))
 
     self.Expect([
       Cmd("git status -s -uno", ""),
       Cmd("git status -s -b -uno", "## some_branch\n"),
       Cmd("git fetch", ""),
       Cmd("git branch", "  branch1\n* branch2\n"),
-      Cmd("git checkout -b %s origin/branch-heads/candidates" %
+      Cmd("git checkout -b %s origin/candidates" %
           TEST_CONFIG["BRANCHNAME"], ""),
       Cmd(("git log --format=%H --grep=\"Port r12345\" "
            "--reverse origin/master"),
           "hash1\nhash2"),
       Cmd("git svn find-rev hash1 origin/master", "45678"),
       Cmd("git log -1 --format=%s hash1", "Title1"),
       Cmd("git svn find-rev hash2 origin/master", "23456"),
       Cmd("git log -1 --format=%s hash2", "Title2"),
       Cmd(("git log --format=%H --grep=\"Port r23456\" "
            "--reverse origin/master"),
@@ skipping 447 matching lines @@
 
 Review URL: https://codereview.chromium.org/83173002
 
 ------------------------------------------------------------------------""")
     self.assertEquals(
 """Prepare push to trunk.  Now working on version 3.23.11.
 
 R=danno@chromium.org
 
 Committed: https://code.google.com/p/v8/source/detail?r=17997""", body)