[代码优化](v2.6)：修复重新登录后重定向参数丢失，具体查看如下 issues

close https://github.com/elunez/eladmin/issues/584

src/views/login.vue

@@ -78,8 +78,10 @@ export default {
         if (data && data.redirect) {
           this.redirect = data.redirect
           delete data.redirect
+          if (JSON.stringify(data) !== '{}') {
             this.redirect = this.redirect + '&' + qs.stringify(data, { indices: false })
           }
+        }
       },
       immediate: true
     }