Please backport r31914 and r31915 from Ruby trunk

[luislavena]

Hello.

Find attached a patch that backports the modifications done by Yui NARUSE to RubyGems code in trunk. Thread is
[ruby-core:36720]. Issue discussed is #4445: http://redmine.ruby-lang.org/issues/4455

This does not apply to master branch of RubyGems, so the patch is against 1.8 branch.

Thank you.

RubyForge Tracker: http://rubyforge.org/tracker/index.php?func=detail&aid=29250&group_id=126&atid=577