swarming: Fix named cache support.

appengine/swarming/tools/start_bot.py

 #!/usr/bin/env python
 # Copyright 2015 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Starts a local bot to connect to a local server."""
 
 import glob
+import logging
 import os
 import signal
 import socket
 import sys
 import tempfile
 import urllib
 
 
 THIS_DIR = os.path.dirname(os.path.abspath(__file__))
 CLIENT_DIR = os.path.join(THIS_DIR, '..', '..', '..', 'client')
@@ skipping 12 matching lines @@
   """
   def __init__(self, swarming_server_url, redirect=True):
     self._tmpdir = tempfile.mkdtemp(prefix='swarming_bot')
     self._swarming_server_url = swarming_server_url
     self._proc = None
     self._logs = {}
     self._redirect = redirect
 
   def wipe_cache(self):
     """Blows away this bot's cache."""
-    cache_dir = os.path.join(self._tmpdir, 'isolated_cache')
-    if os.path.exists(cache_dir):
-      try:
-        file_path.rmtree(cache_dir)
-      except OSError:
-        pass
+    for i in ('c', 'isolated_cache'):
+      cache_dir = os.path.join(self._tmpdir, i)
+      if os.path.exists(cache_dir):
+        try:
+          file_path.rmtree(cache_dir)
+        except OSError:
+          logging.info('Failed to deleted %s', cache_dir)
 
   @property
   def bot_id(self):
     # TODO(maruel): Big assumption.
     return socket.getfqdn().split('.')[0]
 
   @property
   def log(self):
     """Returns the log output. Only set after calling stop()."""
     return '\n'.join(self._logs.itervalues()) if self._logs else None
@@ skipping 85 matching lines @@
     bot.dump_log()
   except KeyboardInterrupt:
     print >> sys.stderr, '<Ctrl-C> received; stopping bot'
   finally:
     exit_code = bot.stop(False)
   return exit_code
 
 
 if __name__ == '__main__':
   sys.exit(main())