JUnit on compile class path doesn't make it to testRuntime class path

In the spock-specs project I've observed the following: If I put JUnit 4.8.1 on the compile class path, tests are run with an older version of JUnit (not sure where that version comes from), resulting in some failing tests. Only if I put JUnit 4.8.1 on the testCompile class path does it make it to the testRuntime class path. For more information, see this thread on the gradle-user list: http://old.nabble.com/Compile-dependencies-no-longer-on-test-runtime-class-path--ts28723918.html

Problem exists in 0.9-preview-1 and preview-2, but not in 0.8.