pub fn require_master(t: &dyn Transport, host: &Host) -> Result<()>Expand description
Refuse to proceed without a control master, naming the command that opens one.
Every job verb needs this, not just run: without it poll, wait,
tail, kill and rm fell through to ssh and reported a generic failure
with exit 1, instead of the documented exit 3 and the recovery command. The
exception is coop host list, whose whole job is to report which hosts
have a master.