fix python-start-or-switch-repl bug

[akirakyle]

Fixes #2872
python-shell-switch-to-shell doesn't create a new python process if one doesn't already exist. Thus when python-start-or-switch-repl was called with SPC m s i without an existing python process running somewhere, you would get the error No inferior Python process running.

[bmag]

Thanks for the contribution, however there's already an open PR (disclaimer: I wrote it) to fix the same problem, see #7070.

[akirakyle]

Ah, I didn't see that! I was getting quite annoyed at SPC m s i not starting a new python process. Hopefully your PR gets merged in soon.