Fix an inverted condition for the "Reopen Revision" action
Summary: Ref T2543. I converted this condition the wrong way, missing a !. I'll cherry-pick this to stable.
Test Plan: No more "Reopen Revision" action available on open revisions.
Reviewed By: chad
Maniphest Tasks: T2543
Differential Revision: https://secure.phabricator.com/D18399