Disable rubinius, it doesn't support ThreadGroup#enclosed?
Disable rubinius, it doesn't support ThreadGroup#enclosed?

We aren't really dependent on ThreadGroup#enclosed? method and frankly
its usage can be removed from invoker. But need to think about it.
In the meanwhile, lets just disable rbx builds for now.

chiliburger/invoker,diskshima/invoker,nisanth074/invoker,chiliburger/invoker,diskshima/invoker,nisanth074/invoker,flanker/invoker,code-mancers/invoker,diskshima/invoker,code-mancers/invoker,flanker/invoker,flanker/invoker,nisanth074/invoker,chiliburger/invoker,code-mancers/invoker