Elasticsearch Integration Test Never Finishes

Elasticsearch version: Works on 2.1.2 fails on 2.2.0 and later
JVM version: 1.8
OS version: Ubuntu 15.10

I have an empty integration test which never finishes. Gradle waits forever for something to complete.

Steps to reproduce:

git clone git@github.com:winstonewert/broken-es-test.git
cd broken-es-test
./gradlew test