Inject pylib first in the path. This ensures that test load the version

test/small/gyptest-small.py

 #!/usr/bin/env python
 
 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """
 Runs small tests.
 """
 
 import imp
 import os
 import sys
 import unittest
 
 import TestGyp
 
 
 test = TestGyp.TestGyp()
 
 # Add pylib to the import path (so tests can import their dependencies).
 # This is consistant with the path.append done in the top file "gyp".
-sys.path.append(os.path.join(test._cwd, 'pylib'))
+sys.path.insert(0, os.path.join(test._cwd, 'pylib'))
 
 # Add new test suites here.
 files_to_test = [
     'pylib/gyp/MSVSSettings_test.py',
     'pylib/gyp/easy_xml_test.py',
     'pylib/gyp/generator/msvs_test.py',
     'pylib/gyp/generator/ninja_test.py',
     'pylib/gyp/generator/xcode_test.py',
     'pylib/gyp/common_test.py',
     'pylib/gyp/input_test.py',
@@ skipping 12 matching lines @@
   suites.append(unittest.defaultTestLoader.loadTestsFromModule(module))
 # Create combined suite.
 all_tests = unittest.TestSuite(suites)
 
 # Run all the tests.
 result = unittest.TextTestRunner(verbosity=2).run(all_tests)
 if result.failures or result.errors:
   test.fail_test()
 
 test.pass_test()