Fix an issue with BuildLogs and web UI during builds
Ref T9123. After recent changes, viewing a live build log from the web UI throws a CSRF exception.
Check start ("this object is an active log"), not live ("this log is open somewhere").
Test Plan: Will push / etc.
Reviewed By: chad
Maniphest Tasks: T9123
Differential Revision: https://secure.phabricator.com/D14185