The 5.18 fix would have been backported some, certainly to 5.16: I should have said "if you are running a perl much earlier than 5.18". I do know it wasn't ported as far as 5.8, which my $work was running at the time - I had to make the patch for that myself, and then come up with a plan to deploy it for a company that had had so many problems with a previous 5.6 -> 5.8 upgrade they had pretty much resolved never to upgrade again.

Happily, the eventual result was that they actually started upgrading perl more regularly again.