The Python stdlib allows override of sys.ps1/ps2 (to make IPython-like dynamic prompts and so on).  I believe it would be a good idea to
support this in doctest too, to cover cases when given application
uses different from defaults settings for the interpreter.

Probably, we could add ps1/2 optional arguments for DoctestParser.__init__().

Some projects already patch doctest module for this, e.g. IPython:
https://github.com/ipython/ipython/blob/master/IPython/testing/plugin/ipdoctest.py
It shouldn't be too hard to port this feature.