Java subprocesses that we launch must be headless.

This is necessary for running tests on the build agents. This only
affects 1.9 because that runs against Java 6 where JMX insists on
starting up AWT even when it doesn't need a GUI.
Java subprocesses that we launch must be headless.

This is necessary for running tests on the build agents. This only
affects 1.9 because that runs against Java 6 where JMX insists on
starting up AWT even when it doesn't need a GUI.
Merge pull request #3023 from benbc/1.9-headless

Java subprocesses that we launch must be headless.
Java subprocesses that we launch must be headless.