Don't use realpath() to determine cache location (#14136)

[iskunk]

Changelog: Fix: Respect symlinked path for cache location.
Docs: Omit

Close #14136

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[memsharded]

This sounds good, I think this can be moved forward.

It would need a "integration" test that covers this case, to make sure this is working and won't be a problem. This test needs to define the symlink scenario that the issue described, and create and use a dummy package from there, generate some file like --format=json and check the paths.

Do you think that you will be able to contribute such test? Please let us know, we can help or we can even contribute the test ourselves. Thanks for your contribution!

[iskunk]

Thanks @memsharded. I doubt I'd be able to write an acceptable test for this from scratch within a reasonable timeframe, but might there be an existing test that is already pretty close to what is needed? Others I could crib relevant bits from? I should be able to mix and match.

[memsharded]

Don't worry about it, I have added a test in c0104a2, that should be enough

[iskunk]

Much obliged, good sir! It would have taken me quite a while to write a test that succinct :-]