git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@32381 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merges r32050 from trunk into ruby_1_9_2.¶
to prevent random number sequence repeatation at forked child
process which has same pid.
reported by Eric Wong. [ruby-core:35765]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@32381 b2dd03c8-39d4-4d8f-98ff-823fe69b080e