bin/60835: grep {n} buggy in multibyte locale

["tnn%nygren.pp.se@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60835
>Category:       bin
>Synopsis:       grep {n} buggy in multibyte locale
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Oct 01 19:00:00 +0000 2026
>Originator:     Tobias Nygren
>Release:        11.99.8
>Organization:
>Environment:
>Description:
echo aa | LC_ALL=C grep -E '([a]|[b]){2}'
aa
echo aa | LC_ALL=en_US.UTF-8 grep -E '([a]|[b]){2}'
# prints nothing

>How-To-Repeat:
See description.
>Fix:
This bug was originally reported by Andreas Schwab from SUSE labs in 2006:
  https://mail-archive.com/bug-grep%gnu.org@localhost/msg00594.html
SUSE at the time shipped a fix which we could consider using:
  https://build.opensuse.org/projects/openSUSE:Evergreen:11.1/packages/grep/files/grep-2.5.1a-mbcset.diff

It shipped with 2.5.1a which is what we currently have so avoids later GPLv3 issues.