Google Endpoint for oauth version 2 has not been updated.

[Malay-Acharya]

Google recently updated there oauth to v2 and the v1 is now bugging for some organisational accounts.

Endpoint Changes

Old: https://accounts.google.com/o/oauth2/auth
New: https://accounts.google.com/o/oauth2/v2/auth

This also supports include_granted_scopes=true for incremental auth.