Bug 1294130

Description of problem:
The following code appears in /usr/lib64/python3.5/site-packages/pymongo/cursor.py:

 972     def __next__(self):
 973         """Advance the cursor."""
 974         if self.__empty:
 975             raise StopIteration
 976         _db = self.__collection.database
 977         if len(self.__data) or self._refresh():
 978             if self.__manipulate:
 979                 return _db._fix_outgoing(self.__data.popleft(),
 980                                          self.__collection)
 981             else:
 982                 return self.__data.popleft()
 983         else:
 984             raise StopIteration
 985 
 986     __next__ = next

That last line replaces the __next__ function with the Python next() builtin, which causes the Cursor not to be iterable. Strangely, the upstream source code that the current Rawhide release is based on does not contain this error:

https://github.com/mongodb/mongo-python-driver/blob/f3931c1e19707eec0afa1f58d2096bd2c1ed2732/pymongo/cursor.py#L972-L986

This is very severe for Python 3 users, but does not seem to affect Python 2 users.


Version-Release number of selected component (if applicable):
$ rpm -q python3-pymongo
python3-pymongo-3.0.3-2.fc24.x86_64


How reproducible:
Every time


Steps to Reproduce:
1. Download the attached reproducer, which uses python3-mongoengine.
2. $ sudo dnf install python3-mongoengine
3. $ python3 mongoengine_test.py


Actual results:
[rbarlow@boole ~]$ python3 mongoengine_test.py 
Traceback (most recent call last):
  File "mongoengine_test.py", line 15, in <module>
    for u in User.objects:
  File "/usr/lib/python3.5/site-packages/mongoengine/queryset/queryset.py", line 80, in _iter_results
    self._populate_cache()
  File "/usr/lib/python3.5/site-packages/mongoengine/queryset/queryset.py", line 92, in _populate_cache
    self._result_cache.append(next(self))
  File "/usr/lib/python3.5/site-packages/mongoengine/queryset/base.py", line 1407, in __next__
    raw_doc = next(self._cursor)
TypeError: next expected at least 1 arguments, got 0


Expected results:
It should look like the output given by running the same script with python2:

[rbarlow@boole ~]$ python2 mongoengine_test.py 
yo
sup