Removing the mutation in the factories for getting dep repositories

appengine/findit/util_scripts/crash_queries/delta_test/run-delta-test.py

 # Copyright 2016 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.
 
 """Runs delta test on two Predator revisions."""
 
 import argparse
 from datetime import date
 from datetime import timedelta
 import logging
@@ skipping 121 matching lines @@
   git_hash2 = delta_util.ParseGitHash(args.revisions[1])
 
   delta_result_prefix = '%s_%s_%s..%s.delta' % (git_hash1[:7], git_hash2[:7],
                                                 args.since, args.until)
   delta_csv_path = os.path.join(DELTA_RESULTS_DIRECTORY,
                                 '%s.csv' % delta_result_prefix)
   delta_path = os.path.join(DELTA_RESULTS_DIRECTORY,
                             delta_result_prefix)
 
   # Check if delta results already existed.
+  # TODO: this code has race conditions for interacting with the file system.
   if os.path.exists(delta_csv_path):
     print 'Delta results existed in\n%s' % delta_csv_path
     if not os.path.exists(delta_path):
       print 'Cannot print out delta results, please open %s to see the results.'
       return
 
     with open(delta_path) as f:
       deltas, crash_num = pickle.load(f)
   else:
     print 'Running delta test...'
     print ('WARNING: Please commit any local change before running delta test, '
            'and do not make any new changes while running the delta test.')
     # Get delta of results between git_hash1 and git_hash2.
     deltas, crash_num = delta_test.DeltaEvaluator(
         git_hash1, git_hash2, args.client, args.app,
         start_date=args.since, end_date=args.until,
         batch_size=args.batch, verbose=args.verbose)
     delta_util.FlushResult([deltas, crash_num], delta_path)
     delta_util.WriteDeltaToCSV(deltas, crash_num, args.app,
                                git_hash1, git_hash2, delta_csv_path)
 
   # Print delta results to users.
   print '\n========================= Summary ========================='
   delta_util.PrintDelta(deltas, crash_num, args.app)
 
 
 if __name__ == '__main__':
   RunDeltaTest()