Still not working with certain letters

Simple reroll for 3.x

I created MR!19 with the patch from #7 to get the tests running.
Apparently every existing test passes.

We need a new test for this case before it gets committed.

Thank you @sanduhrs, great work! Could someone please add a test for these cases?
Do we need other tests due to the modifier addition?

https://www.php.net/manual/en/reference.pcre.pattern.modifiers.php