Steps to reproduce
Login with a existing user account from LDAP.
What is the current bug behavior?
Access denied for your LDAP account.
What is the expected correct behavior?
Let the user connect.
Relevant logs and/or screenshots
(LDAP) Error saving user LDAP_PATH (temp-email-for-oauth-USERID@gitlab.localhost): ["Email has already been taken"]"
Output of checks
It wasn’t an issue before the update to 16.6.0. We used 16.3.4 before. I tried to revert back and same issue. All user except the default admin user can’t login anymore 
.