buildd-queue-builder broken with odd SQLObject problems

When running buildd-queue-builder on the latest rocketfuel, it's refusing to create any builds, on the grounds that no distroarchreleases have chroots.

This in fact isn't true. It appears to be going wrong on this line:

        legal_archs = release_archs.intersection(self._archreleases.keys())

At this point, from extra debugging output I added, both sets appear to contain records relating to the relevant distroarchreleases, but they are different objects with different memory addresses, and which don't compare equal. This of course causes the intersection to be empty and the code to decide none of the archs for this release were amongst the archs for which we found pockets.