Update continue/break for php 7.3
I didn't actually repro this because I don't have php 7.3 installed. I'm also not sure if the break; break was intentional or not, since I'm not sure you could ever reach two consecutive break statements.
Test Plan: Created some projects. Didn't actually try to hit the code that fires if you're making a project both a subproject and a milestone.
Reviewed By: epriestley
Differential Revision: https://secure.phabricator.com/D19925