scripts: repl: Extend REPL %load-path with all channels.

Fixes <https://bugs.gnu.org/61343>.
Reported by 宋文武 <iyzsong@envs.net>.

* guix/scripts/repl.scm (define-command): Before starting the REPL,
call 'current-profile' to populate (%package-module-path).

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

guix/scripts/repl.scm

@@ -211,6 +211,7 @@ call THUNK."
               ((guile)
                (save-module-excursion
                 (lambda ()
+                  (current-profile) ;populate (%package-module-path); see above
                   (set-user-module)
                   ;; Do not exit repl on SIGINT.
                   ((@@ (ice-9 top-repl) call-with-sigint)