No 404 on registration subpage

[SGr33n]

Hi,

If you try to load a page like www.buddypress.org/registration/test/ it will not send you to a 404 page, instead it will show the registration page.

[djpaul]

In 8658:

Core: match the registration route precisely.

Previously, you could enter the registration route with non-existent
parts, such as /registration/test/, and BuddyPress would serve up the
registration template.

By checking if bp_current_action() is set (the /test/ part), we can
bail out of bp_core_screen_signup(). BuddyPress will correctly 404
these incorrect URLs.

Fixes #5772

[DJPaul]

Bah, typo'd the commit message (should be /register/test/).