This bug occurs when an atomic pattern is matched at the end of
a string and the on-failure-keep-string-jump optimisation is
in effect, as in:
(string-match "\\'\\(?:ab\\)*\\'" "a")
which succeeded but clearly should not (bug#58726).
Reported by Michael Heerdegen.
* src/regex-emacs.c (PREFETCH): Add reset parameter.
(re_match_2_internal): Use it for proper atomic pattern treatment.
* test/src/regex-emacs-tests.el (regexp-atomic-failure): New test.
