Using mg with Ruby 1.9.1 produces LOTS of warnings

[jamesarosen]

When using mg with Ruby 1.9.1-p378 (using RVM on OSX), I get LOTS of warnings about gemspecs. Some examples:

WARNING:  #<NoMethodError: undefined method `>' for nil:NilClass> (Rake 0.8.7)
WARNING:  Invalid .gemspec format in '~/.rvm/gems/ruby-1.9.1-p378@global/specifications/rake-0.8.7.gemspec'

WARNING:  #<NoMethodError: undefined method `>' for nil:NilClass> (RDoc 2.5.6)
WARNING:  Invalid .gemspec format in '~/.rvm/gems/ruby-1.9.1-p378@global/specifications/rdoc-2.5.6.gemspec'

And so on for update_rubygems, abstract, actionmailer, and just about every other gem on my system.