Experimental patch for http://github.com/macks/ruby-protobuf/issues#issue/3

gistfile1.diff

diff --git a/lib/protobuf/message/message.rb b/lib/protobuf/message/message.rb
index 3083618..856a128 100644
--- a/lib/protobuf/message/message.rb
+++ b/lib/protobuf/message/message.rb
@@ -120,7 +120,7 @@ module Protobuf
     def initialize(values={})
       @values = {}

-      self.class.fields.each do |tag, field|
+      self.class.fields.to_a.each do |tag, field|
         unless field.ready?
           field = field.setup
           self.class.class_eval {@fields[tag] = field}
@@ -131,7 +131,7 @@ module Protobuf
       end

       # TODO
-      self.class.extension_fields.each do |tag, field|
+      self.class.extension_fields.to_a.each do |tag, field|
         unless field.ready?
           field = field.setup
           self.class.class_eval {@extension_fields[tag] = field}