If for some reason the bitbake server dies, we shouldn't loop indefinitely
waiting for events within tinfoil. Add a ping test and exit if things
have somehow failed.
(Bitbake rev: 32da768ae67cfe0b2d154ce4667a7cfdfa5bf4b0)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>