FIX: only allow one user to be created per invite

app/models/invite_redeemer.rb

@@ -11,7 +11,7 @@ InviteRedeemer = Struct.new(:invite, :username, :name, :password, :user_custom_f
     # If `invite_passthrough_hours` is defined, allow them to re-use the invite link
     # to login again.
     if invite.redeemed_at && invite.redeemed_at >= SiteSetting.invite_passthrough_hours.hours.ago
-      return invited_user
+      return get_existing_user
     end
 
     nil