Lack of any hooks for user registration in case of multisite installation AND BuddyPress

[summoner]

Hi there,
Recently i get quite a few strange registrations so i wanted to implement a captcha to the registration form. I have WP multisite and BP 2.3.2 installed.

One of my sites has no BuddyPress and just a normal registration, for this one it was really easy to get what i wanted: with "signup_extra_fields" hook i display the captcha and with "add_signup_meta" hook i can validate the captcha before any data is saved to the database.

But when BP is enabled on a multisite installation, there is simply no hook defined in wpmu_signup_user function found in ms-functions.php. That way it seems to be impossible to validate the the captcha with add_filter before the user is saved WP's "signup" table. This way one can not protect against spam registrations.

Please consider adding a proper hook in WP 4.3. It is just a short line of code and can not break anything but that way the signup process would become controllable without modification of a core function.