dgrnbrg/autotest — comment on commit 4401e8351d3bbae61b5f326c8815701b38bf8171
File: server/hosts/site_factory.py line 38
By dgrnbrg:

The killer bits do nothing if the process terminates normally. They just also allow a kill -9 to be sent to the process without requiring any special features in the SSH client (the ssh spec allows sending signals to remote clients, but no one's implemented it so it's an unused portion.