Pulp

The Content Serializer causes a 500 error on uploads.

http --form POST http://localhost:8000/api/v3/artifacts/ file@./foo.tar.gz 

This returns a 500. It looks like `hexdigest()` requires a "length" argument. Here's the traceback in journalctl:

Jan 23 18:43:37 pulp3.dev pulp[22901]: django.request:ERROR: Internal Server Error: /api/v3/artifacts/
                                       Traceback (most recent call last):
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner
                                           response = get_response(request)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 249, in _legacy_get_response
                                           response = self._get_response(request)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response
                                           response = self.process_exception_by_middleware(e, request)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response
                                           response = wrapped_callback(request, *callback_args, **callback_kwargs)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
                                           return view_func(*args, **kwargs)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/viewsets.py", line 95, in view
                                           return self.dispatch(request, *args, **kwargs)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 494, in dispatch
                                           response = self.handle_exception(exc)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 454, in handle_exception
                                           self.raise_uncaught_exception(exc)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 491, in dispatch
                                           response = handler(request, *args, **kwargs)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/mixins.py", line 20, in create
                                           serializer.is_valid(raise_exception=True)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/serializers.py", line 236, in is_valid
                                           self._validated_data = self.run_validation(self.initial_data)
                                         File "/home/vagrant/.virtualenvs/pulp/lib64/python3.6/site-packages/rest_framework/serializers.py", line 438, in run_validation
                                           value = self.validate(value)
                                         File "/home/vagrant/devel/pulp/pulpcore/pulpcore/app/serializers/content.py", line 97, in validate
                                           digest = data['file'].hashers[algorithm].hexdigest()
                                       TypeError: Required argument 'length' (pos 1) not found