[PATCH] posix: fix false regex match with backrefs and $ anchor

[Collin Funk]

Dropping bug-gnulib, since my message doesn't apply there.

Paul Eggert <eggert@cs.ucla.edu> writes:

> On 2026-04-13 10:40, Florian Weimer wrote:
>> Wouldn't it make sense to call check_halt_state_context only once?
>
> Yes it would, and thanks. I installed the attached into Gnulib, and we
> should propagate this into glibc when we propagate the other fixes.

Thanks, I had planned to send the other fixes separately with bug
reports after this one. I figured glibc would prefer things that way.

I submitted a v2 with your adjustments [1]. In case anyone is wondering
why the links it my commit messages lead to nowhere, GNU's cgit and
gitweb interfaces haven't picked up commits since a week ago. They
should work once that is fixed. I sent a message to
savannah-hackers-public.

Collin

[1] https://inbox.sourceware.org/libc-alpha/d2fb83f75b54b6be662a2501bc3c6a2d68dfd0b0.1776115137.git.collin.funk1@gmail.com/T/#u