Workaround Travis CI issue by hardcoding localhost

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60656 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/library/net/http/http/fixtures/http_server.rb

@@ -64,7 +64,7 @@ module NetHTTPSpecs
 
     def start_server
       server_config = {
-        BindAddress: "localhost",
+        BindAddress: "127.0.0.1",
         Port: 0,
         Logger: WEBrick::Log.new(NullWriter.new),
         AccessLog: [],