Fixed the pretest filename

expect_tests/pipeline.py

 # Copyright 2014 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.
 
 import contextlib
 import imp
 import inspect
 import logging
 import multiprocessing
 import os
@@ skipping 381 matching lines @@
   This function is meant to be run as a dedicated process. Calling it twice
   in the same process is not supported.
 
   Args:
     cover_ctx:
     kill_switch (multiprocessing.Event):
     result_queue (multiprocessing.Queue):
     opts: output of argparse.ArgumentParser.parse_args (see main.py)
     processing_context (ProcessingContext): the task to perform.
     """
-  pretest_filename = os.path.join(processing_context.cwd, '.expect_tests.py')
+  assert os.path.isabs(processing_context.cwd)
+  # pretest_filename can officially be accessed by .expect_tests_pretest.py to
+  # get to this file's location. So no renaming!
+  pretest_filename = os.path.join(processing_context.cwd,
+                                  '.expect_tests_pretest.py')
   if os.path.isfile(pretest_filename):
     execfile(pretest_filename)
 
   sys.path.insert(0, processing_context.cwd)
 
   # This flag is set when test generation has finished.
   test_gen_finished = multiprocessing.Event()
   test_queue = multiprocessing.Queue()
 
   with TempDir() as temp_dir:
@@ skipping 113 matching lines @@
 
     if procs:
       error = opts.handler.result_stage_loop(opts, generate_objects(procs))
   except ResultStageAbort:
     pass
 
   if not kill_switch.is_set() and not result_queue.empty():
     error = True
 
   return error, kill_switch.is_set()