See http://rubygems.org/read/chapter/16
Currently, RAILS_GEM_VERSION is hardcoded to always be an exactly equal version.
This patch allows any advanced versioning to be used for RAILS_GEM_VERSION, either via a constant in environment.rb, or the RAILS_GEM_VERSION environment variable. It also allows spaces. The hardcoded equal in the 'gem' method version parameter was not needed for backward compatibility, that's the default anyway.
This will allow sophisticated use of RAILS_GEM_VERSION, such as specifying RAILS_GEM_VERISON='> 1.2.5' to float on the latest beta gem version.
Tests are provided, and I've manually tested it using various version specs in environment.rb and RAILS_GEM_VERSION environment var.
Thx,
-- Chad