rubygems tests fail on zlib dependency if you compile ruby without zlib headers
Currently if you don't have zlib headers installed and you run the tests, it yields:
C:/dev/ruby/downloads/ruby_trunk/test/rubygems/test_gem_spec_fetcher.rb: no such file to load -- zlib
repeat many times
I'd suggest that core fallback on a pure ruby zlib if a C one isn't installed.
of course, there's no pure ruby openssl so I'm not sure if this would actually be enough to allow rubygems tests to run, but it would still in general be nice.