Adding support for magic_comment generated encoding comments

lib/annotate/annotate_models.rb

@@ -212,7 +212,7 @@ module AnnotateModels
         old_columns = old_header && old_header.scan(column_pattern).sort
         new_columns = new_header && new_header.scan(column_pattern).sort
 
-        encoding = Regexp.new(/(^#\s*encoding:.*\n)|(^# coding:.*\n)|(^# -\*- coding:.*\n)/)
+        encoding = Regexp.new(/(^#\s*encoding:.*\n)|(^# coding:.*\n)|(^# -\*- coding:.*\n)|(^# -\*- encoding\s?:.*\n)/)
         encoding_header = old_content.match(encoding).to_s
 
         if old_columns == new_columns && !options[:force]