CSS optimization/aggregation fails on files that use specific variations of @import

The previous patch did not run tests. I attached the same patch with a different filename.

I created a merge request, since patches are no longer tested.

Thanks for working on this! It seems like there is still some work needed.

Issue summary seems to be outdated, as we are not fixing relative paths, but @imports.
Parent issue updated the tests, here the test changes are missing.

I am also a bit confused about #25, which states that the issue no longer affected D8 (13 years ago) and then there was a commit/fix in D9 3 years ago (in this issue #2936067: CSS aggregation fails on many variations of @import → , started 7 years ago). So we need to be sure what we are fixing here.

Comment #9 🐛 CSS optimization/aggregation fails on files that use specific variations of @import Needs work changed from CSS optmization fails on relative paths to CSS optmization fails on css files that use @import, although the same comment still describes the issue being with relative paths.

#2936067: CSS aggregation fails on many variations of @import → does not seem to fix an issue with relative paths. It seems this issue and that issue are not related.
We should check for an issue for Drupal 8+ which changes the regular expression this issue propose to change.

Comment #25 🐛 CSS optimization/aggregation fails on files that use specific variations of @import Needs work seems to hit the nail.

The bug is no longer in Drupal 8. While the replacement string wasn't changed, the pattern was fixed to only match the string up to the (optional) opening quote. Instead of capturing the actual path, it is now only checked with a lookahead assertion that makes sure it is not an absolute URL (starting with / or a protocol identifier).