About 4500 (out of 2.8 million) accounts were mis-notified of potential upcoming renaming due to a bug in the script. The users contacted had been renamed, in some cases a very long time ago, and their old username talk pages redirect to their current account name talk page.
These accounts need contacted. Pathoschild put together a list of affected accounts and I've written a message that is currently up for translation. I'll paste it over here when complete.