Comment 22 for bug 1449062

The alternative approach is to modify oslo.concurrency processutils.execute method to allow limits to be passed in explicitly, and then use the pre-exec function to set them between fork + exec. This is actually the more desirable architectural approach, but I didn't go that way, since while it is fine for master, it would not be something that's easily backported to stable branches due to the need to update the min required oslo.concurrency version dependancy.