Testing error in PL Callback

[enochkan]

Please refer to the issue here

Testing PL Callback results in HTTP error 403 (similar to this issue). There are simple workarounds in test_pl_callback using urllib such as:

def set_header_for(self):
         opener = urllib.request.build_opener()
         opener.addheaders = [("User-agent", "Mozilla/5.0")]
         urllib.request.install_opener(opener)

     def prepare_data(self):
         self.set_header_for()
         # download only
         MNIST(
             "/tmp/keepsake-test-mnist",

However it breaks the overall build, hence further investigation is needed.

[bfirsh]

Thanks! This is the real fix: #551