Comment by sync

This one seems pretty amateur and should have been caught as part of a pull request/code review process.

   - @regex = /^(#{Regexp.escape(@prefix)})(.+?)(#{Regexp.escape(@suffix)})$/
   + @regex = /\A(#{Regexp.escape(@prefix)})(.+?)(#{Regexp.escape(@suffix)})\z/

^ and $ only match the first line in ruby, whereas \A and \z match across all lines.