strip python subprocess prefix to enable python shell detections

[Granitosaurus]

This fixes #26

$ ps -ww -o "pid=" -o "ppid=" -o "args="                                                                              
  17309    1624 /usr/bin/python -u /usr/bin/xonsh
  30755   17309 /usr/bin/ps -ww -o pid= -o ppid= -o args=
$ python -c "import shellingham;print(shellingham.detect_shell())"                                                    
('xonsh', '/usr/bin/xonsh')

[uranusjr]

What I’m afraid of is this might cause false positives when the user runs a scrip called (say) bash. It would probably be a good idea to only allow stripping for chosen shells (e.g. xonsh).

[Granitosaurus]

@uranusjr Could you clarify on the false positive issue? Right now if the first argument contains python -> remove first argument and any argument with leading -. I guess if the process is called my-python-shell it would break but that's kinda expected as my-python-shell would be unhandled anyways.

[uranusjr]

I can kind of conceive a situation someone names a script handling bash stuff like ~/.local/bash. Not very likely by any means, but it’s better to be safe. What I have in mind is basically what you’re doing, but only if the replacement found ends with xonsh.

[Granitosaurus]

I can kind of conceive a situation someone names a script handling bash stuff like ~/.local/bash. Not very likely by any means, but it’s better to be safe. What I have in mind is basically what you’re doing, but only if the replacement found ends with xonsh.

Sounds fair! Let me take an attempt at this approach.

[Granitosaurus]

@uranusjr ☝️ - change to handle xonsh explicitly.

[uranusjr]

I pushed a tidied up version of this in #28. Could you help test whether that works?