Ensure connect callback is invoked on premature socket hangup

Closes brianc#534

Author: Sandro Santilli

lib/client.js

@@ -167,6 +167,7 @@ Client.prototype.connect = function(callback) {
         self.emit('error', error);
       } else {
         callback(error);
+        callback = null;
       }
     } else {
       //need to sync after error during a prepared statement
@@ -180,6 +181,13 @@ Client.prototype.connect = function(callback) {
   });
 
   con.once('end', function() {
+    if ( callback ) {
+      // haven't received a connection message yet !
+      var err = new Error("Stream unexpectedly ended before getting ready for query execution");
+      callback(err);
+      callback = null;
+      return;
+    }
     if(self.activeQuery) {
       self.activeQuery.handleError(new Error('Stream unexpectedly ended during query execution'));
       self.activeQuery = null;