Added much more error-recovery logic to template-verifier -- e.g. it retries a few times to fetch the master from the web.  Also I changed the master to live in the system global tempdir, mostly because the build machines had a network problem and I wanted to reduce the chance of that happening.  Not reviewed, but I'm checking it in over the weekend so I can silently fix it if there's yet another weird configuration difference that breaks it on the build machines.