* ext/digest/digest.c (rb_digest_instance_equal):
fix #== for non-string arguments. [ruby-core:62967] [Bug #9913]
* test/digest/test_digest.rb: add test for above.
* ext/digest/digest.c (rb_digest_instance_equal): no need to call
`to_s` twice. [Bug #9913]
merge revision(s) 46368,46371: [Backport #9913]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@47333 b2dd03c8-39d4-4d8f-98ff-823fe69b080e