Summary:
If the server certificates have expired, then the returned token will no longer be valid as soon as the certificates are renewed.
So, validate this before returning any existing token.
This was not an issue before, as launching used to be the last step during bootstrapping.
Reviewed By: antonk52
Differential Revision: D48902334
fbshipit-source-id: 2458aa0df806db245994ee742f42bff47a533e23