[rubygems/rubygems] require uri in source.rb

https://github.com/rubygems/rubygems/commit/8de4d0272e

lib/rubygems/source.rb

@@ -28,6 +28,7 @@ class Gem::Source
   # Creates a new Source which will use the index located at +uri+.
 
   def initialize(uri)
+    require "uri"
     begin
       unless uri.kind_of? URI
         uri = URI.parse(uri.to_s)