我正在尝试从 RVM 到我的 MacBook 进行全新安装，并且我在 RVM 要求方面做了很多工作。我开始单独安装，但我有这个错误：
$ rvm requirements
Installing requirements for osx, might require sudo password.
Already up-to-date.
Installing required packages: libxml2, libxslt........
Error running 'requirements_osx_brew_libs_install libxml2 libxslt',
please read /Users/myuser/.rvm/log/1370499182_package_install_libxml2_libxslt.log
日志包含以下消息：
[2013-06-05 23:00:55] requirements_osx_brew_libs_install
Error: No such keg: /usr/local/Cellar/libxml2
Warning: For non-brewed Python, you have to set the PYTHONPATH in order to
find brewed Python modules.
export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH
Error: File exists - /usr/local/lib/python2.7/site-packages
There were package installation errors, make sure to read the log.
Check Homebrew requirements https://github.com/mxcl/homebrew/wiki/Installation
我正在安装 RVM 来处理 Ruby on Rails 项目。
希望您能指导我，谢谢！