Fix windows file URLs

[valtron]

Ensure that file URLs created from windows paths are valid, i.e. look like file:///C:/foo/bar. Additionally I saw a few places where preexec_fn was being used on windows, so I added guards there.

Test results:

• Before: 554 failed, 889 passed, 395 skipped, 6 warnings, 107 errors
• After: 379 failed, 1080 passed, 395 skipped, 8 warnings, 91 errors

Related: #8474

[ThomasWaldmann]

Some feedback. Windows file URLs confuse me. :)

[ThomasWaldmann]

Linter is unhappy.

Maybe do that to avoid this automatically: https://borgbackup.readthedocs.io/en/master/development.html#building-a-development-environment

[codecov]

Codecov Report

❌ Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.05%. Comparing base (a329890) to head (1f76b6a).
⚠️ Report is 14 commits behind head on master.

Files with missing lines	Patch %	Lines
src/borg/repository.py	71.42%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9097      +/-   ##
==========================================
- Coverage   81.07%   81.05%   -0.03%     
==========================================
  Files          77       77              
  Lines       13540    13554      +14     
  Branches     2008     2011       +3     
==========================================
+ Hits        10978    10986       +8     
- Misses       1900     1904       +4     
- Partials      662      664       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ThomasWaldmann]

Thanks!

Are changes in borgstore needed also?

[ThomasWaldmann]

Hmm, looks like I overlooked another linter fail. I fixed it in #9108.

[valtron]

Are changes in borgstore needed also?

I didn't have any, and haven't run into any other issues so far.

[ThomasWaldmann]

@valtron can you have a look at #8727?

I think there is a small overlap between what was fixed here and the fixes there, but it could be that we still need some fixes from there.