merge revision(s) 39475: [Backport #7868]

	* ext/date/date_core.c: [ruby-core:52303]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39676 b2dd03c8-39d4-4d8f-98ff-823fe69b080e