coverage never generates in com.android.test modules

[matejdro]

com.android.test modules do not appear to produce any *.ec files for code coverage when running its test.

Steps:

1. Download CoverageDemoApp.zip
2. Run instrumented tests in the app module.
3. Note that app/build/outputs/code_coverage folder contains coverage files
4. Run instrumented tests in the testmodule module.

BUG: testmodule/build/outputs/code_coverage folder is empty

Attached project is just a new hello world Android project with a test module added in.