Failed to create a new user from an agreement reply email.

[cyberhobo]

We sometimes get the existing_user_login error from WordPress. This is mysterious because it's thrown when username_exists() returns true, and we've already used that function to create a username where it returns false:

postmatic-basic/core/user-handling.php

Line 55 in 0ec1741

} while ( username_exists( $username ) );