use pip install --user when --as_root pip:false, rather than pip install

[k-okada]

Current implementation runs pip install command when --as-root pip:false is set.
In most cases, it does not work because it try to install the pip package under /usr/local without sudo command
So when we set --as-root, I think we should use pip install --user command.

[codecov-io]

Codecov Report

Merging #693 into master will increase coverage by 0.16%.
The diff coverage is 96%.

@@            Coverage Diff             @@
##           master     #693      +/-   ##
==========================================
+ Coverage   75.47%   75.63%   +0.16%     
==========================================
  Files          32       32              
  Lines        2968     2996      +28     
==========================================
+ Hits         2240     2266      +26     
- Misses        728      730       +2

Impacted Files	Coverage Δ
src/rosdep2/platforms/pip.py	67.24% <100%> (+2.42%)	⬆️
src/rosdep2/installers.py	78.36% <100%> (+0.08%)	⬆️
src/rosdep2/main.py	50.36% <95.55%> (+1.77%)	⬆️

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[NikolausDemmel]

The original use case of adding this was on macos, where the system-wide install in /usr/local for brewed python shouldn't be done with root. So I don't think we should change the default.

Maybe instead some syntax like --installer-args "pip:--user" could be used.

[k-okada]

thanks for feedback, to be clear, "brewed python" means python on osx/homebrew? -- ◉ Kei Okada 2019年7月18日(木) 19:23 Nikolaus Demmel <[email protected]>:

…

The original use case of adding this was on macos, where the system-wide install in /usr/local for brewed python shouldn't be done with root. So I don't think we should change the default. Maybe instead some syntax like --installer-args "pip:--user" could be used. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#693?email_source=notifications&email_token=AADYNXA7EA4UIFU6PKVIHWDQABADLA5CNFSM4IEWTJEKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD2IBEPI#issuecomment-512758333>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADYNXFLWARDD5EVBWPWUSTQABADLANCNFSM4IEWTJEA> .

[NikolausDemmel]

Yes, exactly, it means the python installed with homebrew (as opposed to the one shipped with macos). You can still do pip install --user, and maybe that is even a better idea if you are the only user for the ROS setup on that machine. I personally don't mind the change too much, but maybe some users rely on the current behaviour.

[NikolausDemmel]

Oh look, there was already discussion on supporting --user back when --as-root was added, but nothing came of it in the end: #307 (comment)

[k-okada]

@NikolausDemmel thanks for comment, I have implemented —installer-options and add rosdep/config.yaml to support —user

[nuclearsandwich]

@k-okada in addition to needing a rebase there are quite a few changes here which I think could be split out. I'm especially interested in the optparse -> argparse commits and I think the introduction of a config file to persist options will come with its own discussion and would benefit from a breakout PR as well. Would you be willing to open either or both of those?