Push Command.destroy down through DispatchCommand redirection

When we redirect through a DispatchCommand to a different name we
need to ensure the destroy event is pushed down too, in case the
daemon terminates before the command is run.

Change-Id: Idc4446f4a0426aadcbb03c48ff2321071cded25b
Signed-off-by: Shawn O. Pearce <sop@google.com>