Roslaunch can't terminate grandchildren

[stonier]

Linux uses group id's for a process and all it's children. So if roslaunch starts a process, it simply sends a kill to this group id.

The same python function isn't available on windows, so we need a different method. Currently it doesn't do anything except kill the child, so any processes started by that child will just hang as zombies.

We'll tackle it if we have a use case that suddenly requires it. If someone else wants to hit this bug, let me know and I can point them at the code.