Update a Mercurial test to top accessing a non-existent Bitbucket repo.
Review Request #11152 — Created Aug. 30, 2020 and submitted
We had an online-only unit test for Mercurial that attempted to query
something from the pypy repository on Bitbucket. This doesn't exist now,
since Bitbucket doesn't support Mercurial anymore, preventing the test
This change fixes the test to access content from the main Mercurial
repository instead. The test is also altered slightly to ensure that
the revision is properly considered alongside the filename.
Unit tests pass.