Upgrade to coverage 3.7.1 and have it auto-build itself on first use.

scripts/slave/unittests/recipe_configs_test.py

 #!/usr/bin/python
 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Provides test coverage for common recipe configurations.
 
 recipe config expectations are located in ../recipe_configs_test/*.expected
 
 In training mode, this will loop over every config item in ../recipe_configs.py
 crossed with every platform, and spit out the as_json() representation to
 ../recipe_configs_test
 
 You must have 100% coverage of ../recipe_configs.py for this test to pass.
 """
 
 import argparse
 import multiprocessing
 import os
 import sys
 from itertools import product, imap
 
-import test_env  # "relative import" pylint: disable=W0403
+import test_env  # "relative import" pylint: disable=W0403,W0611
 
 from slave import recipe_loader
 from slave import recipe_util
 
 import coverage
 
 SCRIPT_PATH = os.path.abspath(os.path.dirname(__file__))
 SLAVE_DIR = os.path.abspath(os.path.join(SCRIPT_PATH, os.pardir))
 
 COVERAGE = (lambda: coverage.coverage(
@@ skipping 105 matching lines @@
   coverage_parallel_map(evaluate_configurations)
 
   retcode = 0
 
   COVERAGE.combine()
   total_covered = COVERAGE.report()
   if total_covered != 100.0:
     print 'FATAL: Recipes configs are not at 100% coverage.'
     retcode = 2
 
-  test_env.print_coverage_warning()
-
   return retcode
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))