reported by @milessabin at https://gitter.im/scala/contributors?at=57d6c250a0e8dbb04f2f86e7

the resulting misbehavior is that if you try to use sbt's set scalaHome := Some(new java.io.File(...)) feature (either via scalaHome or via e.g. ++2.12.0-RC1=/Users/tisue/... and run tests you get java.lang.NoClassDefFoundError: org/scalatools/testing/Framework