Comment 12 for bug 724893

This is worth fixing, but as far as I know:
 * when it fails, it fails safely (no corruption, just the import fails and can potentially be retried)
 * it's not actually triggering often
 * it's not utterly trivial to fix (needs some consideration of what db we want to use, or whether we want to work around sqlite limits)
 * we can deal with it when we hit it

So, downgrading.