Swarming tests: Fix uninteresting hash file path

infra/bots/common.py

 #!/usr/bin/env python
 #
 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 
 import contextlib
 import math
@@ skipping 278 matching lines @@
       # This must run before we write anything into self.device_dirs.dm_dir
       # or we may end up deleting our output on machines where they're the same.
       host_dm_dir = os.path.join(self.swarm_out_dir, 'dm')
       print 'host dm dir: %s' % host_dm_dir
       self.flavor.create_clean_host_dir(host_dm_dir)
       if str(host_dm_dir) != str(self.device_dirs.dm_dir):
         self.flavor.create_clean_device_dir(self.device_dirs.dm_dir)
 
       # Obtain the list of already-generated hashes.
       hash_filename = 'uninteresting_hashes.txt'
-      host_hashes_file = self.tmp_dir.join(hash_filename)
+      host_hashes_file = os.path.join(self.tmp_dir, hash_filename)
       hashes_file = self.flavor.device_path_join(
           self.device_dirs.tmp_dir, hash_filename)
 
       try:
         get_uninteresting_hashes(host_hashes_file)
       except Exception:
         pass
 
       if os.path.exists(host_hashes_file):
         self.flavor.copy_file_to_device(host_hashes_file, hashes_file)
@@ skipping 49 matching lines @@
 
     # See skia:2789.
     if ('Valgrind' in self.name and
         self.builder_cfg.get('cpu_or_gpu') == 'GPU'):
       abandonGpuContext = list(args)
       abandonGpuContext.append('--abandonGpuContext')
       self.flavor.run(abandonGpuContext)
       preAbandonGpuContext = list(args)
       preAbandonGpuContext.append('--preAbandonGpuContext')
       self.flavor.run(preAbandonGpuContext)