modify typo.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@2120 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/net/http.rb

@@ -1297,7 +1297,7 @@ module Net
         HTTPUnknownResponse
       end
 
-      def each_response_header( sock, res )
+      def each_response_header( sock )
         while true do
           line = sock.readuntil( "\n", true )   # ignore EOF
           line.sub!( /\s+\z/, '' )              # don't use chop!