Hi Guix,

I've attached a patch for a simple rubygem. This one was slightly nasty 
because the gem for version 1.0.1 includes the .gem file for version 
1.0.0, which means that 1.0.0 gets silently installed instead of the 
built and tested 1.0.1 .gem file - it is unlucky that 
"pkg/ruby-engine-1.0.0.gem" is lexicographically before 
"ruby-engine-1.0.1.gem".

While I managed to install 1.0.1, I wasn't sure how best to remove the 
bundled 1.0.0 .gem file. The issue is that when the source is a .gem 
file (ie most of the time), the gemspec is taken from the downloaded 
.gem file directly, and in the same phase the .gem file is built. So as 
a packager there is no way to make changes to the gemspec without 
replacing the entire build phase. There's a number of rubygems that are 
contaminated with junk so it would be great for there to be a simple way 
to modify the gemspec before "gem build" is run.

Would someone with more experience like to suggest a way of doing this? 
A new "gemspec" phase before "build" that takes the gemspec out of the 
.gem so the packager can manipulate it perhaps?

It would also be good to check that there is only one .gem file.

Thanks,
ben