Merge branch 'mk/workaround-pcre-jit-ucp-bug'

A recent-ish change to allow unicode character classes to be used with "grep -P" triggered a JIT bug in older pcre2 libraries. The problematic change in Git built with these older libraries has been disabled to work around the bug. * mk/workaround-pcre-jit-ucp-bug: grep: work around UTF-8 related JIT bug in PCRE2 <= 10.34