add `.destroy` proxy method into CM

lib/dialects/abstract/connection-manager.js

@@ -113,6 +113,9 @@ ConnectionManager.prototype.initPools = function () {
           self.pool.write.acquire(callback, priority);
         }
       },
+      destroy: function(connection) {
+        return self.pool[connection.queryType].destroy(connection);
+      },
       drain: function() {
         self.pool.read.drain();
         self.pool.write.drain();

lib/dialects/mysql/connection-manager.js

@@ -67,12 +67,8 @@ ConnectionManager.prototype.connect = function(config) {
         // See [stackoverflow answer](http://stackoverflow.com/questions/20210522/nodejs-mysql-error-connection-lost-the-server-closed-the-connection)
         connection.on('error', function (err) {
           if (err.code === 'PROTOCOL_CONNECTION_LOST') {
-
-            // Get the right read/write pool in case of replication, otherwise use generic pool
-            var pool = config.replication ? self.pool[connection.queryType] : self.pool;
-
             // Remove it from read/write pool
-            pool.destroy(connection);
+            self.pool.destroy(connection);
           }
         });
       }