Due to a bug during a refactor late in 4.0.x, we were attempting to

store a raw Revision object in extra_data. The intent of the code

was to convert a revision to something we could store by using

convert_to_unicode() and factoring in the repository's configured

encoding list. However, this didn't know how to convert Revision

objects.
We received a patch that addresses this by performing a conversion

before passing it in, which guaranteed we'd get a string out of it. This

used force_str()/force_text(). However, that performs its decoding

from byte strings to Unicode strings, and makes its own assumptions

about the encoding type that should be used. That could result in an

incorrectly-decoded string.
This isn't a major issue for revisions on most SCMs, which are generally

using ASCII (though, there's no guarantee here). However, the filename

was also force-decoded prematurely, which could impact some setups.
This change removes the force-decoding for filenames entirely, which was

probably just added as a "just in case" measure, and then does a very

explicit Revision to bytes conversion before passing to

convert_to_unicode(). This is the safest way to handle this, avoiding

the heuristics in Django's string conversion machinery, and gets us the

result we want.
Unit tests were added to cover this case.

Unit tests pass. Verified the new test case failed with the reported

error without the fix.