bug#28580: python.el: native completion setup failed

[Noam Postavsky <npostavs@users.sourceforge.net>]

I've pushed a change [1: b33808ce77] so that errors will be more helpful
(at least for the case in the original report), e.g., when missing
readline, you would now see something along the lines of:

>>> python.el: native completion setup failed, <type 'exceptions.ImportError'>: No module named readline

[1: b33808ce77]: 2017-10-02 23:15:43 -0400
  Give more helpful messages for python completion setup failures
  http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=b33808ce77ef15c1f233790a2c93d9db4cc588ab>

Андрей Парамонов <cmr.pent@gmail.com> writes:

> 2017-09-25 0:31 GMT+03:00 Noam Postavsky <
> npostavs@users.sourceforge.net>:
>
>     You can find it here: http://git.savannah.gnu.org/cgit/emacs.git/
>     tree/lisp/progmodes/python.el?h=emacs-25.3
>    
>     Make sure to evaluate the changed source *after* you've loaded
>     the
>     builtin python.el.
>
> I'll try to find time to debug it.

Actually, I think this troubleshooting code I posted earlier would be
helpful in your case as well:
https://debbugs.gnu.org/cgi/bugreport.cgi?filename=py-native-completion.el;att=1;msg=35;bug=25753

Replace "python2" with the name of your python executable, and run via

    emacs -Q -l py-native-completion.el

post the output found in the "*py native complete test*" buffer.