Long delay with no status printed when running after changing gradle version

## Steps to Reproduce

1. `flutter create test01`
1. `cd test01`
1. `flutter build apk`
1. Edit `android/gradle/gradle.properties` to point to some new gradle version (e.g., 3.5)
1. `flutter run`

=> tool prints: 'Launching lib/main.dart on Nexus 5X in debug mode...', and then nothing happens and no status is printed for almost 30 seconds.
