我正在尝试使用 .scss 将 font-awesome 更新到最新版本。
当我尝试使用 campass 进行编译时，它会引发此错误：
>>> Change detected at 17:51:13 to: ui/_font_awesome.scss
NoMethodError on line ["323"] of /usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb: undefined method `perform' for nil:NilClass
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:321:in `map'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:321:in `run_interp_no_strip'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:331:in `run_interp'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:295:in `visit_directive'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:37:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:20:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:146:in `block in visit_import'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:146:in `map'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:146:in `visit_import'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:37:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:20:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:146:in `block in visit_import'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:146:in `map'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:146:in `visit_import'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:37:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:20:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:53:in `map'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:53:in `visit_children'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:29:in `block in visit_children'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:41:in `with_environment'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:28:in `visit_children'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:37:in `block in visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:49:in `visit_root'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/base.rb:37:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:20:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/visitors/perform.rb:7:in `visit'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/tree/root_node.rb:20:in `render'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/engine.rb:305:in `_render'
/usr/local/lib/ruby/gems/1.9.1/gems/sass-3.2.0.alpha.64/lib/sass/engine.rb:252:in `render'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:140:in `block (2 levels) in compile'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:126:in `timed'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:139:in `block in compile'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/logger.rb:45:in `red'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:138:in `compile'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:118:in `compile_if_required'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:103:in `block (2 levels) in run'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:101:in `each'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:101:in `block in run'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:126:in `timed'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/compiler.rb:100:in `run'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/commands/watch_project.rb:147:in `recompile'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/path.rb:73:in `call'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/path.rb:73:in `run_callback'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/path.rb:55:in `callback_action'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/path.rb:35:in `update'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/state/directory.rb:39:in `block in modified'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/state/directory.rb:37:in `each'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/state/directory.rb:37:in `modified'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/state/directory.rb:18:in `refresh'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/backends/inotify.rb:12:in `block in add_handler'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/notifier.rb:200:in `call'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/notifier.rb:200:in `block in watch'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/watcher.rb:41:in `[]'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/watcher.rb:41:in `callback!'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/event.rb:128:in `callback!'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/notifier.rb:233:in `block in process'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/notifier.rb:233:in `each'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/notifier.rb:233:in `process'
/usr/local/lib/ruby/gems/1.9.1/gems/rb-inotify-0.8.8/lib/rb-inotify/notifier.rb:216:in `run'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/backends/inotify.rb:20:in `run'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm/monitor.rb:26:in `run'
/usr/local/lib/ruby/gems/1.9.1/gems/fssm-0.2.8.1/lib/fssm.rb:70:in `monitor'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/commands/watch_project.rb:87:in `perform'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/commands/base.rb:18:in `execute'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/commands/project_base.rb:19:in `execute'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/exec/sub_command_ui.rb:43:in `perform!'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/lib/compass/exec/sub_command_ui.rb:15:in `run!'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/bin/compass:29:in `block in <top (required)>'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/bin/compass:43:in `call'
/usr/local/lib/ruby/gems/1.9.1/gems/compass-0.12.1/bin/compass:43:in `<top (required)>'
/usr/local/bin/compass:19:in `load'
/usr/local/bin/compass:19:in `<main>'
我花了整个下午寻找有同样问题的人，但没有找到任何东西......
任何猜测可能是什么问题？
泰！