feat(checker): add mp4v2 checker

[ffontaine]

windows_fixup must be moved to util.py to reuse this function in test_condensed_downloads.py

[terriko]

Not sure what's going on here, but windows is failing with the following error:

   Error: error: invalid path 'test/condensed-downloads/libmp4v2-1:2.1.3-2-aarch64.pkg.tar.xz.tar.gz'
  Error: The process 'C:\Program Files\Git\bin\git.exe' failed with exit code 128

If I had to guess, the problem character in the filename is : but it could be some other windows filesystem limitation.

[ffontaine]

I don't know how to fix it and unfortunately I didn't find other mp4v2 binary packages on other distributions (debian, etc.)

[terriko]

I think it'll take a change in how we build filenames from the urls in make_condensed_from_download. I believe we need to run the filename through a filter before we make/access the local file. I probably won't get to it until after the 3.4 release is done, but maybe I can file an issue or something now.

[terriko]

#4418 should have fixed this, so I'll update the branch and let the tests re-run.

[terriko]

I see you found a new place the code was needed. Thanks!