We wrote a custom auth plugin back against 1.9, and ported it to Moodle 2.X (I believe it was Moodle 2.1), and it has a custom forgot_password.php and forgot_password_form.php implementation.
In our case we wanted to force users to retrieve password by email adress only, as users found having the option of doing username OR email address confusing.
Somewhere along the way, it appears that our custom auth forgot password page is no longer getting picked up.
We are currently running Moodle 2.3.2
I'm not seeing anything in auth_plugin_base that I need ot be implementing or extending to cause the custom forgot_password form to be used (similar to loginpage_hook())
Is this no longer possible? Am I missing something? (More likely)