Make distutils symlink_data command private

[cottsay]

We don't want anyone taking a dependency on this functionality, and we don't want to interfere with non-colcon use of setuptools or distutils, so it's best to just hide this entry point and make it available only when we're running our builds.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.44%. Comparing base (b174608) to head (f46b170).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #645   +/-   ##
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  Coverage   83.43%   83.44%           
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  Files          66       66           
  Lines        3816     3817    +1     
  Branches      745      745           
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+ Hits         3184     3185    +1     
  Misses        555      555           
  Partials       77       77           

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[nuclearsandwich]

I understand and agree with the why of this change and want to confirm that I understand the how as well.

1. The entrypoint configuration is removed from the package configuration in setup.cfg
2. Data files representing a vendored/stashed python module with entrypoints are installed with colcon-core
3. In colcon core's build task, this vendored/stashed module is added to the PYTHONPATH directly at the point before its used.

Is that about correct?

[cottsay]

Is that about correct?

Nailed it.

I discounted this as an option when it was originally implemented, but the Python metadata specification is actually pretty simple so it was easy to dump it in there. We're already modifying the PYTHONPATH when we invoke the build in order to change the installation locations via the site customization, so it isn't a very far reach to also inject some setuptools nonsense here.

All of this will be deprecated by colcon-python-project code at some point.

[nuclearsandwich]

Nailed it.

Thanks for confirming!

All of this will be deprecated by colcon-python-project code at some point.

May the day be soon at hand!