after the first initscr() sigwinch is handled as expected, but then my 
app needs to ignore sigwinch, leave curses to view the output from 
something, come back into curses, and start listening for sigwinch 
again. The signal(SIGWINCH, SIG_IGN) call doesn't return the old, 
working signal handler; it returns 0 -- thus trying to re-set the 
signal handler doesn't work.

(The reason for ignoring the signal is that if the window is resized 
while the external app is running, python's wait() is interrupted)

Having the handler visible from python would also make curses play 
nicer with readline, as the app could mediate signal handling (see 
issue #3948)