Add some tests for remove_prefix

[tomaka]

Adds some tests regarding the code added in #2663

I wanted to maybe figure out why #2666 was failing, but didn't manage to find a failing case.

[mergify]

Automatically approving tomaka's pull requests. This auto-approval will be removed once more maintainers are active.

[github-actions]

twiggy diff report

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[melekes]

👍