Refs #23763 -- Fixed Python 3.5 PendingDeprecationWarning in LazyStream.

Fixed "PendingDeprecationWarning: generator 'LazyStream.read.<locals>.parts'
raised StopIteration" per PEP 0479.

django/http/multipartparser.py

@@ -327,8 +327,11 @@ class LazyStream(six.Iterator):
             while remaining != 0:
                 assert remaining > 0, 'remaining bytes to read should never go negative'
 
+                try:
                     chunk = next(self)
-
+                except StopIteration:
+                    return
+                else:
                     emitting = chunk[:remaining]
                     self.unget(chunk[remaining:])
                     remaining -= len(emitting)