Happened after receiving a push hook.

Traceback (most recent call last):
  File "/usr/lib/python3.4/threading.py", line 920, in _bootstrap_inner
    self.run()
  File "XXX/managetests/frontend/__init__.py", line 46, in run
    self.manager.process_hook(data)
  File "XXX/managetests/app.py", line 130, in process_hook
    self._process_push_hook(data)
  File "XXX/managetests/app.py", line 148, in _process_push_hook
    self.load_branch(branch, mr)
  File "XXX/managetests/app.py", line 90, in load_branch
    branch.deploy()
  File "XXX/managetests/branches.py", line 102, in deploy
    "rm -rf %s/%s/*" % (self.caches_dir, self.name),
AttributeError: 'Branch' object has no attribute 'caches_dir'