Don't rebuild darkbot when lock file is there

Summary:
Running a highstate in test mode on Eglide,
I notice it offers to run the darkbot_build
state.

Test Plan: salt eglide state.apply roles/shellserver/odderon test=True

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1124