Download from actual location with mirror

[X-dark]

Description

File location is not always in the same location as the directory. Fetch real url from dir listing when using mirror.

Related Issue(s)

#113 and probably #99

Checklist

• [X] This PR does not need a documentation change

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• [X] This PR's changes are already tested

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• [X] This change is not user-facing
• [X] This change is a patch change

Changes made

• created new function getFileURL to obtain mirror URL for a given file
• used it to generate file location for archive and hash

[komish]

Thanks for the submission. I believe this should be fixed, however - there was a broken redirect that should now be working.