There is a regression bug that prevents a UI warning from displaying when trying to create a user with a default email address (i.e. [email protected]). The UI warning displays in a clean 6.2.10 bundle, but not in Master.
The regression was caused by
Two UI errors should appear, "Your request failed to complete" and "Please enter a valid email address".
Only the first UI error appears. "Please enter a valid email address" does not appear.