Code review comment for lp:~vila/bzr/353370-notty-no-term-width

I think this is ok to land as it is, but eventually the priority we want is

1- BZR_COLUMNS
2- TIOCGWINSZ if possible (or the equivalent for win32)
3- COLUMNS otherwise
4- otherwise None

also fwiw http://www.ohse.de/uwe/software/resize.c.html suggests checking TIOCGSIZE too