This builder: https://ci.chromium.org/p/flutter/builders/try/Linux%20flutter_plugins
e.g. https://ci.chromium.org/p/flutter/builders/try/Linux%20flutter_plugins/1858

Here and several other cases, pub get failed. Instead of printing the error and exiting, the test just hangs until it times out.

@godofredoc @keyonghan