GitHub is still hosting the full youtube-dl version history, including versions which include those supposedly infringing tests. Does copyright law end with HEAD on master? Those tests are still there. This makes it especially obvious that the RIAA's problem with youtube-dl was never really the tests.
With regards to copyright law and "distribution", there's no distinction. The tests are still being "distributed", just from a different URL. If youtube-dl was in violation before, they still are now.
This is a confusing result. I would not expect any copyright litigant to sacrifice legal advantage for the sake of an adversary's convenience in maintaining complete version control history.
Could there possibly have been a miscommunication over what "remove the tests" meant? Or an offer of compromise outside of legal necessity? Or a bad-faith fulfillment of a promise to "remove the tests"?