Bisecting gives me 3acd55740d447b2afb47ab5da5e3eece93337829 as the first bad commit. bug_19856 (https://gitweb.torproject.org/user/gk/tor-browser-bundle.git/commit/?h=bug_19856) has a possible fix reverting to libfaketime for the gitian-utils part for OS X which fixes the problem for me. I am open to better solutions, though, if we can get to one before we need to build the next alpha.
Trac: Status: new to needs_review Keywords: TorBrowserTeam201608 deleted, GeorgKoppen201608, TorBrowserTeam201608R added