I've kept that in mind when reviewing, and I see no reason not to just merge this now.  I think it should be backwards compatible.

Of course, it would be best to actually test that an old-style fallback still works when launched with this branch deployed on lantern_aws. :)

Then again, lantern_aws doesn't have a lot of activity and I don't expect this to fall out of sync too badly if we wait for 'pluggabletransports' to be ready to deploy.

Maybe let's do this: if I make any changes to lantern_aws, I'll start from this branch, so we amortize the testing pain.