FileLocator.relative_filename() could mangle the path too much in some unlikely cases

[nedbat]

Originally reported by Marius Gedminas (Bitbucket: mgedmin, GitHub: mgedmin)

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If your working directory is /src/myproject and you happen to have your source files in /src/myproject/branchname/src/myproject/foo.py, FileLocator().relative_filename() will strip both '/src/myproject/' substrings from the path, leaving just 'branchnamefoo.py'.

I'm attaching a test case and a fix.

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• Bitbucket: https://bitbucket.org/ned/coveragepy/issue/194
• This issue had attachments: fix-relative-filename.diff. See the original issue for details.

[nedbat]

Thanks, fixed! I used s.replace(prefix, "", 1), though. <<changeset 12a4c06a41ad (bb)>>.