server is doing auth for user 'Administrator' in ldap if previous login is a ldap authentication

1. Configure CB Server with LDAP and also with ldap group support
2. Configure with ldap group and assign it a admin role
3. Add a user to ldap group
4. Now login via the ldap user. 
5. Now login via "Administrator" 

Logs show:

[ns_server:debug,2019-01-10T01:32:45.214-08:00,ns_1@127.0.0.1:<0.25671.0>:ldap_util:with_connection:31]Connected to LDAP server

[ns_server:debug,2019-01-10T01:32:45.519-08:00,ns_1@127.0.0.1:<0.25671.0>:ldap_util:with_authenticated_connection:61]Bind for dn "<ud>cn=Administrator,ou=Users,dc=couchbase,dc=com</ud>":

{error,                                                                        invalidCredentials}

[ns_server:debug,2019-01-10T01:32:45.519-08:00,ns_1@127.0.0.1:ns_audit<0.392.0>:ns_audit:handle_call:114]Audit login_failure: [{real_userid,{[

{domain,rejected},

                                     {user,<<"<ud>Administrator</ud>">>}]}},

                      {remote,{[{ip,<<"10.112.180.1">>},\{port,52648}]}},

                      {timestamp,<<"2019-01-10T01:32:45.519-08:00">>}]

[ns_server:debug,2019-01-10T01:32:55.006-08:00,ns_1@127.0.0.1:ns_audit<0.392.0>:ns_audit:handle_call:114]Audit login_failure: [{real_userid,{[{domain,rejected}

,

                                    

{user,<<"<ud>Administrator</ud>">>}]}},

                      {remote,{[{ip,<<"10.112.180.1">>},\{port,52648}]}},

                      {timestamp,<<"2019-01-10T01:32:55.006-08:00">>}]

 

Now wait for few seconds and refresh the browser and then try to login again.  This time it is 'Administrator' as builtin user.

[ns_server:debug,2019-01-10T01:33:04.541-08:00,ns_1@127.0.0.1:ns_audit<0.392.0>:ns_audit:handle_call:114]Audit login_success: [{roles,[<<"admin">>]},

                      {real_userid,{[{domain,builtin},

                                     {user,<<"<ud>Administrator</ud>">>}

]}},

                     

{sessionid,<<"01ee24aa72430d20cad09f394fd88294">>}

,

                      {remote,{[

{ip,<<"10.112.180.1">>}

,{port,52648}]}},

                     

{timestamp,<<"2019-01-10T01:33:04.541-08:00">>}

]