Sergey, I understand that, but I don't care.  The only people I've ever seen _use_ this are people writing an entirely different shell interface.  They're rare.  There's no value in complicating doctest to cater to theoretical use cases that don't exist - to the contrary, that's counterproductive complication.

As your IPython example showed, their job is harder than _just_ replacing PS1/PS2.  See their `parse()` function.  They want to cater both to IPython's PS1/PS2 conventions _and_ to the standard CPython terminal shell PS1/PS2 conventions.

But they don't cater to _more_ than just those either.  Why should they?  Same thing here:  extra complication for no good reason.