* src/regex-emacs.c (analyze_first): Fix incorrect optimization

* src/regex-emacs.c (analyze_first): Fix incorrect optimization

The optimization was incorrect in a particular corner case.
In this fix I just disable it conservatively for more cases because
it's not obvious how to fix it while preserving the "good" cases.

We may find a better fix by using an approach like the one
in `mutually_exhaustive_aux`, but for now this is good enough,
especially since \{..\} repetitions are not used very frequently.

* test/src/regex-resources/PTESTS: New test.