GPSignIn trySilentAuthentication doesnt refresh token

How does the product behavior differ from your expectations?

If call trySilentAuthentication after token expires in Google Plus iOS SDK, 
delegate callback finishedWithAuth:error: still returns not valid auth object 
with old access token and expire date

Describe, step-by-step, how to reproduce this issue.
1. Sign in explicitly via google plus iOS SDK
2. Wait until token expires - 1 hour
3. Check finishedWithAuth:error: delegate method - it calls with old auth 
object with old expired token.

Bug is reproducible in latest SampleCode

Describe the impact of this bug
Cannot relogin to google plus in app silently, without asking user to go to 
browser

When did this bug start happening?
Happens in SDK 1.7.0 and 1.7.1

When does the bug occur?
100% cases.

Describe any workarounds you have found
No workaround yet, from sample code it looks like if I will call some other 
method SDK method (like load circles or share something) - then token is 
updated and next calls to trySilentAuthentication works fine and returns new 
token. But this way not acceptable if app is using SDK only for oAuth and there 
are no need to call any other sdk method except login

Original issue reported on code.google.com by Golub.Iv...@gmail.com on 19 Sep 2014 at 11:28

Torsten2217 / google-plus-platform

GPSignIn trySilentAuthentication doesnt refresh token #981