While this could be a bug, it is more likely to be an issue with your script. The only way to be sure is to use debugging in your script. For example, you can use debugging in this way:

Code:
away.system.auto {
  echo away.system : %away.system
  echo away.system.auto : %away.system.auto
  echo server : $server
  if %away.system == off && %away.system.auto == on && $server != $null {

You should add similar lines before every %variable and $identifier that is used in the script. This will allow you to see at which point the script is not working. If you then run the same script, in the same situation, under both v6.35 and v7.x, you can compare the output to see whether the debug values are different.