PR 23156 [Skip select ttk tests when on Ubuntu] proposes Ubuntu-specific test skips and is given as a justification for PR 28468 [Add platform.freedesktop_osrelease]. However, PR 23474 [Fix timeouts in ttk tests] attempts to correctly address the issue, though proving it does this will be hard as the issue is an intermittent failure and I don't believe any of us can reproduce locally (hence why it was initially blamed on Azure).

Serhiy also raised concerns about skipping on Ubuntu (though for slightly different reasons) and I have attempted to explain the reasoning in https://github.com/python/cpython/pull/23156#issuecomment-732056985.

My problem with using PR 23156 as a justification for PR 28468 is that the changes I proposed were only intended to be temporary (hence why I considered it acceptable to use the os.uname hack rather than something more reliable) and I don't think it, in itself, should cause a permanent API addition.