[HUDSON-2566] improving error message

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@12963 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/TcpSlaveAgentListener.java

@@ -168,7 +168,7 @@ public final class TcpSlaveAgentListener extends Thread {
             }
 
             if(computer.getChannel()!=null) {
-                error(out, "Already connected");
+                error(out, nodeName+" is already connected to this master. Rejecting this connection.");
                 return;
             }