Fix parent project look up logic

[Enkidu93]

I don't know how I missed this! I think I got so caught up in the refactoring that I forgot to add rigorous tests for the most essential change 😵. Added tests to cover this case as well as a couple other things I noticed were not covered.

Fixes #903.

I did not de-duplicate the warnings since after thinking about it more, I wasn't sure if it'd be helpful to see whether this is affecting both SF parallel corpora or just one. Unlike duplicating the versification warnings which could become sizable, this would only ever be one extra message, so I don't know that it's worth it, but I'm open to changing my mind.

---

This change is 

[ddaspit]

@ddaspit reviewed 5 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Enkidu93).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.97%. Comparing base (714891c) to head (e00267c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #904      +/-   ##
==========================================
+ Coverage   67.87%   67.97%   +0.10%     
==========================================
  Files         386      386              
  Lines       21256    21253       -3     
  Branches     2749     2749              
==========================================
+ Hits        14427    14447      +20     
+ Misses       5844     5825      -19     
+ Partials      985      981       -4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.