Cannot register a new account using an email which has been used by GG login

[hynguyen2610]

Reproduce:

• Register a new GG account A1.
• Using A1 to login to TeamRadio by using feature Google login.
• Sign out
• Go to Register, try to register a new account using A1 as email

Result: Cannot register, error message: "Email has already existed".

Discuss: For example I used to login using GG login, but now I don't want to login by that way anymore, I want to login using email and password, so I would register a new account using the same email, but I cannot register. And I can't change password neither, when I logged in using GG login.

[hynguyen2610]

We aggreed that it's acceptable