[v10] Enterprise connections don't strip domain from email

[nicosabena]

Say you have an enterprise connection, with fabrikam.com set as domain (for HRD). If the user types [email protected], he will be asked to type his corporate credentials (both Lock versions will even suggest jon as the username).

If, at this moment, the user types his or her email ​_again_​ (thinking that this is the username Lock is expecting), :)

• In Lock v9 the code automatically strips the domain (@fabrikam.com) (see https://github.com/auth0/lock/blob/v9/index.js#L1144). So, since only the username is sent in the background, authentication succeeds anyway. (By the way, this only works for the first domain of an enterprise connection).
• In Lock v10, the whole email is sent as the username to the authentication endpoint, so the user gets an "Invalid username or password" error.

Is this difference on purpose and users should type the correct username now, or was this an omission and Lock v10 should behave like Lock v9 for this?