Allow mixed anonymous and non-anonymous onion services in the same tor instance
Similar to #21284 (moved), some single onion service users want to be able to use hidden (double onion) services most of the time, and single onion services occasionally with trusted peers.
For example, see the OnionShare use case in: https://lists.torproject.org/pipermail/tor-dev/2017-January/011782.html
One potential anonymity issue is that any introduction and rendezvous points see the single onion service's IP addresses, as does anyone with access to the networks those relays are on.
But anyone with access to the network the single onion service is on also sees its IP address, and that it is creating tor traffic. So I'm not sure how much of a threat this is.