bug#25753: 25.2; Python mode shell interaction not working 100%

[Charles A. Roelli]

> As I've said, I don't think rc2 would change this, but since it's come
> out now, please test it. 

Tested, and it has the same problem.  Here is what *Python* normally
looks like at the start, run from M-x run-python in emacs -Q:

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 26 2016, 12:10:39) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import codecs, os;__pyfile = 
>>> codecs.open('''/var/folders/WP/WPe0Q1iAGc0J7iI6J50jcU+++TI/-Tmp-/py16611qgD''',
>>>  encoding='''utf-8''');__code = 
>>> __pyfile.read().encode('''utf-8''');__pyfile.close();os.remove('''/var/folders/WP/WPe0Q1iAGc0J7iI6J50jcU+++TI/-Tmp-/py16611qgD''');exec(compile(__code,
>>>  '''/var/folders/WP/WPe0Q1iAGc0J7iI6J50jcU+++TI/-Tmp-/py16611qgD''', 
>>> 'exec'));
python.el: native completion setup loaded

It seems like the line starting with ">>> " should not be printed, if
<nyc4bos@aol.com>'s test output is deemed to be running more or less
correctly.  Maybe that can point us in the right direction?

> Can you test the python code from python-shell-completion-native-setup
> outside of Emacs, e.g., save it to a file called 'native-completion.py'
> and then run 'python -i native-completion.py' and then type an
> underscore and hit <tab>.

I get the following:

>>> ___package__
__PYTHON_EL_native_completion_setup
__name__
__doc__
__import__
__debug__

Interestingly, none of the dummy completions pop up.

> Can you try load the attached file in Emacs?  Does it show similar
> output in the "*py native complete test*" buffer?
> 
>     emacs -Q -l py-native-completion.el

I get no completions with this -- here is all that shows up:

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 26 2016, 12:10:39) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> python.el: native completion setup loaded
>>> 

> Also post the contents of buffer " *Python completions redirect*"
> after doing M-x run-python.

- emacs -Q
- M-x run-python
- C-x b " *Python completions redirect*"

It's this: "_   ^H^H" (space in the middle is a tab character).