Fix "phd repository-launch-readonly"
Summary:
- Delete an unreachable block of code.
- Pass "--" to terminate overseer args.
Test Plan: Ran "phd repository-launch-readonly", didn't get argument errors out of the daemon.
Reviewers: jungejason
Reviewed By: jungejason
CC: aran
Differential Revision: https://secure.phabricator.com/D2456