The main problem here is that a change that should have been done as part of an individual's customization was made to a shared configuration file.

Or, y'know, have coloured prompts but place the escape characters such that they don't mess with prompt-detection regexps.

To be precise, what you're suggesting is that we have prompts which are allowed to be colored except for the $/# at the end, because you can't color those without following them by escape characters. And that prompts must have a $/# at the end.

I don't consider that an acceptable solution.