R1:b6031a721fea

Fix a minor issue with killing daemons

Summary: Even if you --force, we can't kill PID 0. This sends the process itself the signal, and terminates it.

Test Plan: See D11786.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D11787