Error on file upload

[Michal Čihař]

Unfortunately I don't have a reproducer and I'm still on 1.10 on production, but I still think it's worth reporting.

On file upload following error is raised:

Traceback:  

File "/usr/lib/python2.7/dist-packages/django/core/handlers/exception.py" in inner
  42.             response = get_response(request)

File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py" in _legacy_get_response
  249.             response = self._get_response(request)

File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py" in _get_response
  178.             response = middleware_method(request, callback, callback_args, callback_kwargs)

File "/usr/lib/python2.7/dist-packages/django/middleware/csrf.py" in process_view
  260.                     request_csrf_token = request.POST.get('csrfmiddlewaretoken', '')

File "/usr/lib/python2.7/dist-packages/django/core/handlers/wsgi.py" in _get_post
  128.             self._load_post_and_files()

File "/usr/lib/python2.7/dist-packages/django/http/request.py" in _load_post_and_files
  299.                 self._post, self._files = self.parse_file_upload(self.META, data)

File "/usr/lib/python2.7/dist-packages/django/http/request.py" in parse_file_upload
  258.         return parser.parse()

File "/usr/lib/python2.7/dist-packages/django/http/multipartparser.py" in parse
  163.                     self.handle_file_complete(old_field_name, counters)

File "/usr/lib/python2.7/dist-packages/django/http/multipartparser.py" in handle_file_complete
  301.             file_obj = handler.file_complete(counters[i])

File "/usr/lib/python2.7/dist-packages/django/core/files/uploadhandler.py" in file_complete
  153.         self.file.seek(0)