framework gems are automatically marked frozen (even when they're not actually frozen)

Could someone review my (first ever) patch?

I was running into a problem on 2-3-stable where rmagick is getting
added to the list of @@framework_gems in GemDependency when I run
'rake test'. Best I can tell, this is because rmagick is loaded before
any of the gem dependencies. Because framework_gem? returns true for
rmagick, when GemDependency#add_load_paths is called for rmagick, it
marks the gem as frozen (which it isn't). GemDependency#frozen? is
memoized, so a proper check is never performed.

When I run 'rake test,' I get:

The following gems have native components that need to be built
  rmagick

You're running:
  ruby 1.8.7.174 at /opt/local/bin/ruby
  rubygems 1.3.4 at /Users/jd/.gem/ruby/1.8, /opt/local/lib/ruby/gems/
1.8

Run `rake gems:build` to build the unbuilt gems.

https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/2825-rmagick-gem-dependency-is-detected-as-unbuilt-even-though-it-isnt-vendored#ticket-2825-3

New version of the fix here:
https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/2825-rmagick-gem-dependency-is-detected-as-unbuilt-even-though-it-isnt-vendored#ticket-2825-8

Could someone review this?