* lisp/isearch.el: C-s C-u M-y reads a string from the kill-ring minibuffer

* lisp/isearch.el (isearch-yank-from-kill-ring): New command
with code moved from isearch-yank-pop.
(isearch-yank-pop): Use isearch-yank-from-kill-ring.
(isearch-yank-pop-only): Add optional arg, and call
isearch-yank-from-kill-ring when the prefix arg is C-u.
https://lists.gnu.org/archive/html/emacs-devel/2021-01/msg00089.html
2 jobs for master in 45 minutes and 40 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #10107
test-filenotify-gio

00:40:12

passed #10108
test-gnustep

00:45:39

 
Name Stage Failure
failed
test-filenotify-gio Test
Ran 20 tests, 18 results as expected, 0 unexpected, 2 skipped (2021-01-14 08:59:13+0000, 112.416629 sec)

2 skipped results:
SKIPPED file-notify-test10-sufficient-resources
SKIPPED file-notify-test10-sufficient-resources-remote

make[1]: Leaving directory '/builds/emacs/emacs/test'
make: Leaving directory '/builds/emacs/emacs/test'
ERROR: Job failed: exit code 1