[api] also fix the comments in the history

Same bug with xmlhash < 1.3

src/api/app/models/bs_request_history.rb

@@ -5,6 +5,10 @@ class BsRequestHistory < ActiveRecord::Base
   validates_inclusion_of :state, :in => VALID_REQUEST_STATES
   validates :commenter, :presence => true
 
+  def state
+    read_attribute(:state).to_sym
+  end
+
   def self.new_from_xml_hash(hash)
     h = BsRequestHistory.new
     h.comment = hash.delete("comment")

src/api/db/migrate/20121213144129_fix_empty_comments2.rb

@@ -0,0 +1,14 @@
+class FixEmptyComments2 < ActiveRecord::Migration
+  def up
+    BsRequestHistory.all.each do |r|
+      next if r.comment.blank?
+      if r.comment.strip == '--- !ruby/hash:Xmlhash::XMLHash {}'
+        r.comment = nil
+        r.save
+      end
+    end
+  end
+
+  def down
+  end
+end

src/api/db/structure.sql

@@ -1009,6 +1009,8 @@ INSERT INTO schema_migrations (version) VALUES ('20121130143300');
 
 INSERT INTO schema_migrations (version) VALUES ('20121213140751');
 
+INSERT INTO schema_migrations (version) VALUES ('20121213144129');
+
 INSERT INTO schema_migrations (version) VALUES ('21');
 
 INSERT INTO schema_migrations (version) VALUES ('22');