avoid loop between cluster gateways

The VIA extension is still needed to avoid some extra work and ugly
messages, but this is enough that it actually works.

This filters out the RemoteSides that are a proxied connection via a
remote gateway to the cluster.

The VIA extension will not filter those out, but will send VIA to them
on connect, which will cause the ones that are accessed via the listed
gateways to be filtered out.

Annex/Cluster.hs

@@ -96,8 +96,8 @@ clusterProxySelector clusteruuid protocolversion = do
   where
 	-- Nodes of the cluster have remote.name.annex-cluster-node
 	-- containing its name. Or they are proxied by a remote
-	-- that has remote.name.annex-cluster-node containing the cluster's
-	-- UUID.
+	-- that has remote.name.annex-cluster-gateway
+	-- containing the cluster's UUID.
 	isnode rs nodeuuids clusternames r = 
 		case remoteAnnexClusterNode (Remote.gitconfig r) of
 			Just names
@@ -106,11 +106,13 @@ clusterProxySelector clusteruuid protocolversion = do
 						ClusterNodeUUID $ Remote.uuid r
 				| otherwise -> False
 			Nothing -> case remoteAnnexProxiedBy (Remote.gitconfig r) of
-				Just proxyuuid -> not $ null $
-					filter (== clusteruuid) $
-					concatMap (remoteAnnexClusterGateway . Remote.gitconfig) $
-					filter (\p -> Remote.uuid p == proxyuuid) rs
-				Nothing -> False
+				Just proxyuuid
+					| Remote.uuid r /= fromClusterUUID clusteruuid -> 
+						not $ null $
+							filter (== clusteruuid) $
+							concatMap (remoteAnnexClusterGateway . Remote.gitconfig) $
+							filter (\p -> Remote.uuid p == proxyuuid) rs
+				_ -> False
 	
 	isclustername clusternames name = 
 		M.lookup name clusternames == Just clusteruuid