* lisp/repeat.el: Fix repeat-keep-prefix to allow customizing it to non-nil.

* lisp/repeat.el: Fix repeat-keep-prefix to allow customizing it to non-nil.

* lisp/repeat.el (repeat-keep-prefix): Add or remove
'repeat-pre-hook' depending on the customized value.
(repeat-mode): Add or remove 'repeat-pre-hook' to/from
'pre-command-hook' when 'repeat-keep-prefix' is non-nil.
(repeat-pre-hook): New function.
(repeat-get-map, repeat-check-map): New function refactored from
'repeat-post-hook'.
(repeat-post-hook): Move some code to smaller functions.
(describe-repeat-maps): Set outline-regexp without ^L.

* test/lisp/repeat-tests.el (repeat-tests-keep-prefix):
Uncomment test case that is fixed now in bug#51281 and bug#55986.