rubygems/rubygems — pull request #386 by mat813 (2012-10-19 16:54:23+00:00)
Title: No reason darwin has a specific treatment.

Now, a version like unknown-freebsd or x86-openbsd will work.

I was having trouble understanding why the last one wasn't working :

```ruby
>> Gem::Platform.new('universal-darwin1').to_s
"universal-darwin-1"
>> Gem::Platform.new('universal-darwin').to_s
"universal-darwin"
>> Gem::Platform.new('universal-freebsd1').to_s
"universal-freebsd-1"
>> Gem::Platform.new('universal-freebsd').to_s
"universal-unknown"
```