Fixed #16137 - Removed kwargs requirement for QuerySet.get_or_create

Thanks wilfred@, poirier, and charettes for work
on the patch.

django/db/models/query.py

@@ -363,8 +363,6 @@ class QuerySet(object):
         Returns a tuple of (object, created), where created is a boolean
         specifying whether an object was created.
         """
-        assert kwargs, \
-                'get_or_create() must be passed at least one keyword argument'
         defaults = kwargs.pop('defaults', {})
         lookup = kwargs.copy()
         for f in self.model._meta.fields: