How to downgrade Rubygem to its dedicated version, on using RVM.

gem update –system 하여 루비젬을 업그레이드 했다가 아래와 같은 수많은 warnings을 보게 된다.

HyoAir:[Projects]$ gem update --system
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 /Users/hyo/.rvm/gems/ruby-1.9.2-p180@global/specifications/bundler-1.0.12.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 /Users/hyo/.rvm/gems/ruby-1.9.2-p180@global/specifications/rake-0.8.7.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 /Users/hyo/.rvm/gems/ruby-1.9.2-p180@global/specifications/bundler-1.0.12.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 /Users/hyo/.rvm/gems/ruby-1.9.2-p180@global/specifications/rake-0.8.7.gemspec:10.
Latest version currently installed. Aborting.
HyoAir:[Projects]$ gem -v
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 /Users/hyo/.rvm/gems/ruby-1.9.2-p180@global/specifications/bundler-1.0.12.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 /Users/hyo/.rvm/gems/ruby-1.9.2-p180@global/specifications/rake-0.8.7.gemspec:10.
1.8.3

이것은 RVM을 사용할 때 버젼별로 전용 rubygem 버젼이 있는데 생뚱맞게 gem update –system 으로 젬버젼을 업그레이드하여 불평을 하는 것이다.
이럴 때는 전용버젼으로 다운그레이드해야 하는데, 아래와 같은 명령어를 실행하면 전용 젬버젼으로 복원된다.

rvm rubygems current

참조 : https://github.com/rspec/rspec-core/issues/345