No data in graph images

[arcao]

Hi Guys,

After apply fix #141, the graph images from Graphite shows "No data" text. Next I found in Graphite exception logs:

Tue May 01 03:47:25 2018 :: Exception Caught
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/graphite/render/datalib.py", line 231, in fetchData
    cachedResults = CarbonLink.query(dbFile.real_metric)
  File "/usr/lib/python2.7/dist-packages/graphite/render/datalib.py", line 140, in query
    results = self.send_request(request)
  File "/usr/lib/python2.7/dist-packages/graphite/render/datalib.py", line 166, in send_request
    result = self.recv_response(conn)
  File "/usr/lib/python2.7/dist-packages/graphite/render/datalib.py", line 181, in recv_response
    return unpickle.loads(body)
  File "/usr/lib/python2.7/dist-packages/graphite/util.py", line 108, in loads
    return pickle_obj.load()
  File "/usr/lib/python2.7/dist-packages/graphite/util.py", line 97, in find_class
    raise pickle.UnpicklingError('Attempting to unpickle unsafe module %s' % module)
UnpicklingError: Attempting to unpickle unsafe module collections 

which is old bug described in graphite-project/graphite-web#608. I applied fix described in that issue, which solve the exception, but graph image still shows "No data".

Any other idea, what could be wrong?