To reproduce:
1. Open project attached by QA
2. Build it for iOS with "a" scene included
3. Run it on device and press "Allow" when the app will request to send push notifications
4. Check console in the Xcode, it will periodically print acquired deviceToken

Expected: deviceToken is acquired correctly and it should be printed to the console
Actual: deviceToken always returns null.

Reproduced with: Unity 5.6.3f1, 2017.1.0p2, 2017.2.0b6, 2017.3.0a3
Devices: iPhone 5 OS 10.1.1, iPhone 7+ OS 10.3.2, iPhone 6+ OS 8.0

Not reproducible on: iPhone 5s OS 9.3.3, iPad Air 2 OS 9.2