RTD: Clear the dirty git index flag

[jhunkeler]

Resolves JP-nnnn

Closes #

The last build (#8642) produced:

Version: 1.15.2.dev10+g2d15511ca.d20240712

RTD modifies indexed files in the repository prior to building the documentation. This change should prevent setuptools_scm from returning a dirty version (.dXXXXXXXX suffix).

See: https://docs.readthedocs.io/en/stable/build-customization.html#avoid-having-a-dirty-git-index

Checklist for PR authors (skip items if you don't have permissions or they are not applicable)

• [ ] added entry in CHANGES.rst within the relevant release section
• [ ] updated or added relevant tests
• [ ] updated relevant documentation
• [ ] added relevant milestone
• [x] added relevant label(s)
• [ ] ran regression tests, post a link to the Jenkins job below. How to run regression tests on a PR
• [ ] All comments are resolved
• [ ] Make sure the JIRA ticket is resolved properly

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 59.60%. Comparing base (136f1d9) to head (eb692d3).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #8644 +/- ## ========================================== - Coverage 59.61% 59.60% -0.01% ========================================== Files 391 391 Lines 39287 39280 -7 ========================================== - Hits 23419 23412 -7 Misses 15868 15868 ```

:umbrella: View full report in Codecov by Sentry.
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[braingram]

I'm seeing a dev version on this docs for this PR:

I think this is expected (since it's not a tagged commit). Is this expected?

[jhunkeler]

Yes, this is expected. This is my local test case:

1. Make a tag

git tag -a 1.10.100 -m "test tag"
pip install -e '.[test,docs]'
(cd docs && make html)

2. Make it dirty

echo '#' >> docs/Makefile
git describe --long --dirty
1.10.100-0-g590ef5d27-dirty

pip install -e .
Successfully installed jwst-1.10.101.dev0+g590ef5d27.d20240715

(cd docs && make html)

3. Clear the dirty flag

git update-index --assume-unchanged docs/Makefile
pip install -e .
Successfully uninstalled jwst-1.10.101.dev0+g590ef5d27.d20240715
Successfully installed jwst-1.10.100

(cd docs && make html)

Note: We marked the local Makefile as "unchanged" even though it is. You can tell git to care about this file again by using --no-assume-unchanged.

git describe --long --dirty
1.10.100-0-g590ef5d27

git update-index --no-assume-unchanged docs/Makefile

git describe --long --dirty
1.10.100-0-g590ef5d27-dirty