Temporarily use an rspec-core branch.

Author: myronmarston

Gemfile

@@ -2,7 +2,7 @@ source "https://rubygems.org"
 
 gemspec
 
-%w[rspec rspec-core rspec-expectations rspec-mocks rspec-collection_matchers rspec-support].each do |lib|
+%w[rspec rspec-expectations rspec-mocks rspec-collection_matchers rspec-support].each do |lib|
   library_path = File.expand_path("../../#{lib}", __FILE__)
   if File.exist?(library_path) && !ENV['USE_GIT_REPOS']
     gem lib, :path => library_path
@@ -11,6 +11,9 @@ gemspec
   end
 end
 
+# TODO: remove this before merging this PR (and after the rspec-core PR is merged)
+gem 'rspec-core', :github => "rspec/rspec-core", :branch => "define-derived-metadata"
+
 ### deps for rdoc.info
 group :documentation do
   gem 'yard',          '0.8.7.3', :require => false