Sass assets:precompile 语法错误,供应商文件夹中有 .css 文件

Sass Syntax Error in assets:precompile with a .css file in vendor folder

我使用 rails 4.1.7 并在 application.css.scss 中包含一个客户 css 模板并放入客户 css 文件(ace.css)在 vender/assets/stylesheets 文件夹中。

application.css.scss:

/*
 *= require bootstrap
 *= require font-awesome
 *= require ace-fonts
 *= require ace  <----
 *= require_self
 *= require attr_filter
 */

I 运行 RAILS_ENV=production bundle exec rake assets:precompile 显示错误:

rake aborted!
Sass::SyntaxError: Invalid CSS after "...th: 991px) and ": expected media expression (e.g. (min-device-width: 800px)), was "only screen and..."
  (in /Users/xushanchuan/projects/newmerger/app/assets/stylesheets/application.css.scss)
(sass):11576
Tasks: TOP => assets:precompile
(See full trace by running task with --trace)

但是当我删除 ace.css 文件时,assets:precompile 有效。为什么 css 文件生成 Sass::SyntaxError?

现在,解决这个问题的唯一方法是删除所谓的错误语法:'only screen and'.