Fix regression in MSSQL ConnectionManager

lib/dialects/mssql/connection-manager.js

@@ -28,16 +28,17 @@ ConnectionManager.prototype.connect = function(config) {
       server: config.host,
       server: config.host,
       /* domain: 'DOMAIN' */
       /* domain: 'DOMAIN' */
       options: {
       options: {
+        port: config.port,
         database: config.database,
         database: config.database,
       }
       }
     };
     };
 
 
-    // only set port if no instance name was provided
-    if(!config.dialectOptions.instanceName){
-      connectionConfig.options.port = config.port;
-    }
-
     if (config.dialectOptions) {
     if (config.dialectOptions) {
+      // only set port if no instance name was provided
+      if (config.dialectOptions.instanceName) {
+        delete connectionConfig.options.port;
+      }
+
       Object.keys(config.dialectOptions).forEach(function(key) {
       Object.keys(config.dialectOptions).forEach(function(key) {
         connectionConfig.options[key] = config.dialectOptions[key];
         connectionConfig.options[key] = config.dialectOptions[key];
       });
       });