title: Google OAuth2 returns Bad Request when logged with multiple accounts
body: <p>When I'm logged in google with multiple accounts</p>
  
  <p><img src="https://i.stack.imgur.com/nBPp5.png" alt=""></p>
  
  <p>and i'm trying to authorize myself at <a href="https://stackoverflow.com/users/login">https://stackoverflow.com/users/login</a> (or any other site using OAuth2) </p>
  
  <p><img src="https://i.stack.imgur.com/AteJs.png" alt=""></p>
  
  <p>I get a <code>Bad Request - Error 400</code></p>
  
  <p><img src="https://i.stack.imgur.com/YN91z.png" alt=""></p>
  
  <p>This doesn't happen when i'm in incognito mode</p>
  
  <p><img src="https://i.stack.imgur.com/MWgiu.png" alt=""></p>
  
  <p>A sample request is the following</p>
  
  <pre><code>https://accounts.google.com/o/oauth2/auth?client_id=717762328687-p17pldm5fteklla3nplbss3ai9slta0a.apps.googleusercontent.com&amp;scope=profile+email&amp;redirect_uri=https%3a%2f%2fstackauth.com%2fauth%2foauth2%2fgoogle&amp;state=%7b%22sid%22%3a1%2c%22st%22%3a%221435c1882569148a8513b8e5ba7f747ac7821aaf558cbb1a28dd11c5c3cb358b%22%2c%22ses%22%3a%22354093ee65ee44e8a24582c78bdb7127%22%7d&amp;response_type=code
  </code></pre>
  
  <p>There are other similar questions like <a href="https://stackoverflow.com/questions/30212728/google-oauth2-and-400-bad-request-bug-on-google-side">Google oauth2 and 400 bad request: Bug on Google side?</a> but are old and marked as fixed bugs.
  How could I fix this?
  Should I add some other parameters to trigger the account selection?</p>