I've sent patch 37994 for git.
If triggers the rebuilt of just under 300 packages, so I guess it's safe
for master?

For grep:
actually our `grep' package has pcre support.
It's grep-final which doesn't:

--8<---------------cut here---------------start------------->8---
(define grep-final
  ;; The final grep.  Gzip holds a reference to it (via zgrep), so it must be
  ;; built before gzip.
  (let ((grep (with-boot5 (package-with-bootstrap-guile grep))))
    (package/inherit grep
                     (inputs (alist-delete "pcre" (package-inputs grep)))
                     (native-inputs `(("perl" ,perl-boot0))))))
--8<---------------cut here---------------end--------------->8---

Is there a reason for removing pcre here?
It does not add more than 2 MiB to the closure size.  Maybe a graph
simplification issue?

-- 
Pierre Neidhardt
https://ambrevar.xyz/