git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@24452 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merges r24328 from trunk into ruby_1_9_1.¶
so that ruby finds gems in ~/.gem/.
(Gem.user_home): reduced version of lib/rubygems.rb's.
Gem.default_path needs it.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@24452 b2dd03c8-39d4-4d8f-98ff-823fe69b080e