quick hack to prefix annotation with encoding (encoding: UTF-8)

lib/annotate/annotate_models.rb

 module AnnotateModels
   class << self
+    UTF8 = "encoding: UTF-8"
+
     # Annotate Models plugin use this header
     COMPAT_PREFIX = "== Schema Info"
     PREFIX = "== Schema Information"
@@ -117,6 +119,7 @@ module AnnotateModels
     def annotate_one_file(file_name, info_block, options={})
       if File.exist?(file_name)
         old_content = File.read(file_name)
+        old_content.sub!(/^# #{UTF8}.*?\n/, '')
 
         # Ignore the Schema version line because it changes with each migration
         header = Regexp.new(/(^# Table name:.*?\n(#.*\n)*\n)/)
@@ -248,7 +251,7 @@ module AnnotateModels
         end
       end
 
-      header = PREFIX.dup
+      header = "#{UTF8.dup}\n# #{PREFIX.dup}"
 
       if options[:include_version]
         version = ActiveRecord::Migrator.current_version rescue 0