Since I've upgraded to appcompat-v7 v21, I get the following compilation errors:
Exception in thread "pool-117-thread-1" com.sun.tools.javac.code.Symbol$CompletionFailure: class file for android.support.v7.app.ActionBar$NavigationMode not found.
Could this be related to https://groups.google.com/forum/#!topic/scala-on-android/zVhoIBqfzZk?
In case this is relevant: I'm using Android Transfuse.
It seems this bug is fixed in the final v21 SDK.