* Backport part of r39166 from trunk [ruby-trunk - Bug #7809]

* lib/rubygems/package.rb:  Include checksums.yaml.gz signatures for
  verification.
* test/rubygems/test_gem_package.rb:  Test for the above.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39227 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-02-14

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@39228 b2dd03c8-39d4-4d8f-98ff-823fe69b080e