Email activation codes not working after update

I have run into a problem that if a user registered on our old site and older version of community builder and never used their activation code sent to them by email to complete the registration process, now this activation code no longer works with our updated site. It throws an error that they are unauthorized to view this page. Now I don't know how often this would even happen, I mean if someone never finished the registration process months ago, they probably wont now, but I am being told to update the function within the UserTable.php file (getUserIDFromActivationCode) and fix it to where it gives them the correct unscrambled id for their activation code. (Sorry for the run-on sentence)

You can probably empty the activation code in _comprofiler table then resave the user in CB > User Management in an attempt to generate a new activation code. Beyond that I've no idea what to suggest as it's not a scenario we are really accounting for. The activation code is based off your unique site secret and database engine. If either are changed all existing activation codes are invalid.