> fsum will pass if 'from math import fsum' is done before it, but I've left such issues for now since there seems to be a debate about how to go about that

For now, you can at least use the "testsetup" directive which will simultaneously allow the doctests to pass but cause the subsequent lines to be hidden in the rendered HTML.  We can always remove the directive at a later date to cause it to display.  See here for an example:

http://bugs.python.org/review/15888/diff/6011/Doc/howto/ipaddress.rst

> - some seem unfixable too

Can you include links to the questionable areas for examples like these (e.g. using the "browse source" page http://hg.python.org/cpython/file/default/ )?  This will make it easier to reference and discuss.