Comment 1 for bug 1551779

There's a few issues here
 - We currently don't support simplestreams for cloud-images; this is being looked at separately, currently blocked because we're not publishing streams yet.
 - To avoid filling the logs with errors, some simplestreams-related code was disabled in Azure, which led the unintended consequence of us ignoring mirrors.
 - Endpoints are different for Azure Resource Manager; and we canonicalize the region names to lowercasewithoutwhitespace, whereas the simplestreams uses Title Case.

So this would be simpler if we had image simplestreams sorted out, but I guess that's not happening just yet. I'll see what I can do for agents in the mean time.