Unclear. If files opened in regular text mode and binary mode, in read mode, write mode, append mode, and update mode, are all the same text object, I think Universal newlines are just another minor variation.
there's enough "Mode U cannot be combined" stuff in the PEP to make me think that they're slightly more than just a minor variation.
I think you can simplify the PEP somewhat by emphasizing the difference. making things simpler is never a bad idea.
Also, changing the mode is a morelocalized change (it's all in fileobject.c).
I'm willing to do the work necessary to provide an alternate factory/constructor. from what I can tell, all that has to be done is is to apply the patch, and do some fairly straight- forward refactoring.
(and perhaps some slight API renaming -- the functions in there are clearly too useful to deserve names like Py_UniversalNewlineFgets -- "there is no permanent place in this world for ugly names" ;-)
so +1 on checking it in as it stands, but -0 on not touching the result until 2.3 final...