I have just released a new bugfix and enhancements release v0.2.5 for OSSubprocess as you can see in .
This new release is thanks to the awesome work of Guillermo Polito . He found a problem (and a fix) that would hung/block the Pharo image in a wait state. This problem has been forever and I have faced it myself. It would only happen when using #waitForExit and under certain scenario. Because of that, I recommend everyone to move to this release.
Aside from that serious bug, he has also done quite some improvements in the tests and in the Travis setup. Once this PR  has been merged and SmalltalkCI updated, our Travis build  should show all green builds for Linux/OSX and Pharo 5.0 and 6.1.
I have also copied the configuration into Pharo 5.0 and 6.0 catalog so as of tomorrow, it should be there.