Incorrect translated string + menu_rebuild() performance issue

I'm reviewing a site with an older version of backup_migrate.

#2017027: Incorrect use of l() in a translated string changed a call from l() to url().

This fixes a performance issue during menu_rebuild() with an empty theme registry cache.

menu_rebuild() triggers this code via backup_migrate_menu()

l() is called.

l() triggers a theme registry rebuild.

This can take several seconds on some sites.

During this time, the router isn't written, so other requests get held in a lock_wait().

This would be fine because it was fixed, except there's a new call to l().

Patch coming up.