Admin notification Email for pending user registration has blank subject line

I'm surprised no one has caught this error before.

Notification Emails sent to the site admin, when a new user registers, have a blank subject line.

I traced the error to line 1639 of user.module which currently reads:

case 'pending_approval_admin_subject':

Whereas it should read:

case 'register_pending_approval_admin_subject':

I've tested this change and it seems to work, however if I'm wrong then please provide an alternative solution.

Thanks.