Previously the gemspec was extracted during the build phase. The problem was that this was then immediately used to build the gem, leaving no ability to modify it before building (without replacing the entire phase). I figure building a gemspec is kind of like a configure, so made the extraction step the configure step.
I built quite a few ruby packages and didn't come across an error, but this does require a rebuild of all ruby packages. The first patch makes the change, and the second is an example of how it can be useful. Thanks in advance for the review. ben [PATCH 1/2] guix: ruby-build-system: Extract gemspec during configure. [PATCH 2/2] gnu: ruby-nokogiri: Update to 1.6.7.2.
