fix: Other dialect duplicated add index problem

Detect is using SQLite to add index

lib/migrations/20150915153700-change-notes-title-to-text.js

@@ -1,11 +1,14 @@
 'use strict'
+const isSQLite = require('../utils').isSQLite
 module.exports = {
   up: function (queryInterface, Sequelize) {
     return queryInterface.changeColumn('Notes', 'title', {
       type: Sequelize.TEXT
     }).then(function () {
+      if (isSQLite(queryInterface.sequelize)) {
         // manual added index will be removed in sqlite
         return queryInterface.addIndex('Notes', ['shortid'])
+      }
     })
   },
 
@@ -13,7 +16,10 @@ module.exports = {
     return queryInterface.changeColumn('Notes', 'title', {
       type: Sequelize.STRING
     }).then(function () {
+      if (isSQLite(queryInterface.sequelize)) {
+        // manual added index will be removed in sqlite
         return queryInterface.addIndex('Notes', ['shortid'])
+      }
     })
   }
 }

lib/utils.js

@@ -0,0 +1,5 @@
+'use strict'
+
+exports.isSQLite = function isSQLite (sequelize) {
+  return sequelize.options.dialect === 'sqlite'
+}