bug#25067: #25067 Emacs pretest 25.1.91 - ipython completion

[npostavs]

Edward Flanigan <eflanigan00@hotmail.com> writes:

> Python 3.5.2 |Anaconda 4.2.0 (64-bit)| (default, Jul 2 2016, 17:53:06)
> IPython 5.1.0 -- An enhanced Interactive Python.
>
> Recipe is the following:
>
> emacs -q
>
> eval-region on this:
>
> (setq
> python-shell-interpreter "ipython3"
> python-shell-interpreter-args "--simple-prompt --pprint")
>
> Then open *Python* which will be ipython 5.1.0
>
> The following don't work anymore in the pre-test
>
> 1.) import num [TAB] shows possible completions in 25.1.1 but doesn't in the 
> pretest
>
> 2.) run afile [TAB] shows possible completions for the files in the directory 
> that match afile*
>
> 3.) cd adirec [TAB] shows possible completions 

The behaviour from 25.1 can be restored by doing

    (add-to-list 'python-shell-completion-native-disabled-interpreters
                 "ipython")

So it looks like the problem is the fix for #24401 which enables native
completion work for python 3.5, also enables it for ipython, but native
completion doesn't actually work for ipython.