Gem从1.5.3升级到1.6+后和升级到1.8+后的问题

在Gem升级到1.8+后出现如下的提示：

NOTE: Gem::Specification#default_executable= is deprecated with no replacement. It will be removed on or after 2011-10-01.
Gem::Specification#default_executable= called from /Library/Ruby/Gems/1.8/specifications/acts_as_ferret-0.5.1.gemspec:10.
NOTE: Gem::Specification#default_executable= is deprecated with no replacement. It will be removed on or after 2011-10-01.
Gem::Specification#default_executable= called from /Library/Ruby/Gems/1.8/specifications/aws-s3-0.6.2.gemspec:10.
NOTE: Gem::Specification#default_executable= is deprecated with no replacement. It will be removed on or after 2011-10-01.
Gem::Specification#default_executable= called from /Library/Ruby/Gems/1.8/specifications/bundler-1.0.0.gemspec:10.
NOTE: Gem::Specification#default_executable= is deprecated with no replacement. It will be removed on or after 2011-10-01.
Gem::Specification#default_executable= called from /Library/Ruby/Gems/1.8/specifications/erubis-2.6.6.gemspec:10.
NOTE: Gem::Specification#default_executable= is deprecated with no replacement. It will be removed on or after 2011-10-01.
Gem::Specification#default_executable= called from /Library/Ruby/Gems/1.8/specifications/json-1.4.6.gemspec:10.

 说的是有一些方法过时了将在2011-10-1日后不再支持，我们需要更新现有的代码。

Gem已经给我们提供了相应的解决方法。

运行下面的代码

sudo gem pristine --all