Customize blocked user message?

Right now if a blocked user attempts to log in I get “There was a problem with your log in: user is blocked [error code: unauthorized]”

I’d like to customize that, but can’t see a way to do it. The wordpress settings for Lock config link here: Lock Configuration Options but there are no settings for blocked users there.

I’ve found references to configuring this in various places, but none seem to work. Has this functionality been removed?