There have been no new builds of b2g since May 25: https://releases.mozilla.com/b2g/
I can't access that site, but I don't think those are the builds that RelEng manages. The ones we run don't publish anything. Eg: https://tbpl.mozilla.org/php/getParsedLog.php?id=12154093&tree=Firefox&full=1. https://tbpl.mozilla.org/ shows a lot a B2g boxes on it.
(In reply to Ben Hearsum [:bhearsum] from comment #1) > I can't access that site, but I don't think those are the builds that RelEng > manages. John Griffin announced these ones last week on b2g-internal.
This is working again; there was a problem with file permissions on the server which was causing the new builds to be invisible.