Allow "python setup.py install --user"

[thehans]

I've been recommended to use --user instead of sudo for python package installs, but this fails for git-imerge

Can this be done in some way that does not require superuser permissions?

$ python setup.py install --user
--
  | running install
  | running bdist_egg
  | running egg_info
  | creating git_imerge.egg-info
  | writing git_imerge.egg-info/PKG-INFO
  | writing dependency_links to git_imerge.egg-info/dependency_links.txt
  | writing entry points to git_imerge.egg-info/entry_points.txt
  | writing top-level names to git_imerge.egg-info/top_level.txt
  | writing manifest file 'git_imerge.egg-info/SOURCES.txt'
  | reading manifest file 'git_imerge.egg-info/SOURCES.txt'
  | reading manifest template 'MANIFEST.in'
  | writing manifest file 'git_imerge.egg-info/SOURCES.txt'
  | installing library code to build/bdist.linux-x86_64/egg
  | running install_lib
  | running build_py
  | creating build
  | creating build/lib
  | copying gitimerge.py -> build/lib
  | creating build/bdist.linux-x86_64
  | creating build/bdist.linux-x86_64/egg
  | copying build/lib/gitimerge.py -> build/bdist.linux-x86_64/egg
  | byte-compiling build/bdist.linux-x86_64/egg/gitimerge.py to gitimerge.cpython-38.pyc
  | installing package data to build/bdist.linux-x86_64/egg
  | running install_data
  | copying completions/git-imerge -> /usr/share/bash-completion/completions
  | error: could not create '/usr/share/bash-completion/completions/git-imerge': Permission denied

[mhagger]

I'm no expert on python package installs and am not likely to have time to figure this out anytime soon. If anybody has a suggestion (preferably in the form of a PR :-) ), don't be shy!