Code review comment for lp:~spiv/bzr/sigwinch-without-signalmodule-583941

Robert Collins wrote:
> Why does the has_function cause spew?

Why indeed! Here's what happens if I tweak the check to look for
NO_SUCH_FUNCTION rather than sigaction:

$ make
building extension modules.
python setup.py build_ext -i
tmp/NO_SUCH_FUNCTION1nRZ2y.o: In function `main':
NO_SUCH_FUNCTION1nRZ2y.c:(.text+0x7): undefined reference to `NO_SUCH_FUNCTION'
collect2: ld returned 1 exit status
running build_ext

> Also, why do we override COLUMNS when we get sigwinch, thats non obvious to me.

I'm not sure, but as I was targetting this fix to 2.1.x I thought it best to
disturb the existing behaviour as little as possible.