currentSession return null at login

[yukulele]

at login time, if you make call to currentSession() and make a 2nd call before first is resolved, you get null

way to reproduce the bug

• add this piece of code to demo/components/AuthButtons.js :

auth.currentSession().then(session => console.log('currentSession 1', session))
auth.currentSession().then(session => console.log('currentSession 2', session))
auth.currentSession().then(session => console.log('currentSession 3', session))

• exec npm run start:demo
• click "Log in" button
• finalize login process

expected result

console should display:

"currentSession 1",  Object {...}
"currentSession 2",  Object {...}
"currentSession 3",  Object {...}

actual result

console show:

"currentSession 2",  null
"currentSession 3",  null
"currentSession 1",  Object {...}