rather than PUT-FROM or ALREADY-HAVE. Verify that the client processes
that ok and displays it to the user.
+* If a special remote outputs to stdout, or reads from stdin, that will
+ mess up the P2P protocol. Move the special remote proxying into a
+ separate process perhaps, which can be run with stdout and stdin
+ redirected? Or, fix any special remotes that might do that. Are
+ there any left? External special remotes certainly don't since that would
+ mess up their own protocol. Hook special remotes can though.
+
* Streaming download from proxied special remotes. See design.
* Check annex.diskreserve when proxying for special remotes.