A minimal reproducer Finagle's bug with Scala 2.12 (see twitter/finagle#581).

This dead-locks with Scala 2.12.1 but works fine with 2.11.7.

To reproduce:

1. clone the repo
2. cd scala-2-12-1-and-runnable-bug
3. sbt ++2.11.7 run (program finishes)
4. sbt ++2.12.1 run (program dead-locks)*