/usr/share/fish/completions/python2.fish is in fish-common 2.4.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | complete -c python2 -w python
# Override this to use python2 instead of python
complete -c python2 -s m -d 'Run library module as a script (terminates option list)' -xa '(python2 -c "import pkgutil; print(\'\n\'.join([p[1] for p in pkgutil.iter_modules()]))")'
|