This didn't work previously because we had to check whether the incoming
command was an alias command, but if it wasn't we still used the result
of that lookup - which was by the command's node name. That fails for
non-top-level commands. In this case, the resolution is pretty simple since
we already have the node's CommandObject, so all we needed to do was turn
it into a shared pointer, for which I added enable_shared_from_this to the
CommandObject.
Differential Revision: https://reviews.llvm.org/D137662
d518ed42ae