Alternate{Dir,Bridge}Authority aren't sufficient for fully internal TestingTorNetwork

I had several issues getting chutney working on OS X 10.9 with tor 0.2.6.?-alpha. I've diagnosed and patched most of them in #13161 (moved). But I can't seem to stop the chutney bridges* flavours accessing the global tor network rather than the chutney network.

tor git d6b2a1709d28c656dadc019fb24145e6ac400771 + #13161 (moved) chutney git 60b2d18d81904e6a71a352dfa8b5cb73f4e04003 + #13161 (moved)

== Issue Description

Despite being configured as a test network, the chutney bridges* flavours seem to be ignoring TestingTorNetwork, and instead using the global Tor network. Which is really strange, because they all have TestNetwork on in common.i.

I can't work out why this is - perhaps it has something to do with AlternateBridgeAuthority, as that's the only real difference I can see.

I'm not sure what's happening here, and whether it's a bug in tor or chutney. (All other flavours work fine.)

I've attached example torrc files generated by chutney, one of each type. These include changes from #13161 (moved).