proxy updates location tracking information

This does mean a redundant write to the git-annex branch. But,
it means that two clients can be using the same proxy, and after
one sends a file to a proxied remote, the other only has to pull from
the proxy to learn about that. It does not need to pull from every
remote behind the proxy (which it couldn't do anyway as git repo
access is not currently proxied).

Anyway, the overhead of this in git-annex branch writes is no worse
than eg, sending a file to a repository where git-annex assistant
is running, which then sends the file on to a remote, and updates
the git-annex branch then. Indeed, when the assistant also drops
the local copy, that results in more writes to the git-annex branch.

Command/P2PStdIO.hs

@@ -16,6 +16,8 @@ import qualified Annex
 import Annex.UUID
 import qualified CmdLine.GitAnnexShell.Checks as Checks
 import Remote.Helper.Ssh (openP2PShellConnection', closeP2PShellConnection)
+import Logs.Location
+import qualified Remote
 
 import System.IO.Error
 
@@ -68,15 +70,20 @@ performProxy clientuuid servermode remote = do
   where
 	withclientversion clientside (Just (clientmaxversion, othermsg)) =
 		connectremote clientmaxversion $ \remoteside ->
-			proxy done servermode clientside remoteside 
+			proxy done proxymethods servermode clientside remoteside 
 				othermsg protoerrhandler
 	withclientversion _ Nothing = done
 	
+	proxymethods = ProxyMethods
+		{ removedContent = \u k -> logChange k u InfoMissing
+		, addedContent = \u k -> logChange k u InfoPresent
+		}
+
 	-- FIXME: Support special remotes.
 	connectremote clientmaxversion cont = 
 		openP2PShellConnection' remote clientmaxversion >>= \case
 			Just conn@(P2P.IO.OpenConnection (remoterunst, remoteconn, _)) ->
-				cont (RemoteSide remoterunst remoteconn)
+				cont (RemoteSide remoterunst remoteconn (Remote.uuid remote))
 					`finally` liftIO (closeP2PShellConnection conn)
 			_  -> giveup "Unable to connect to remote."