Code review comment for lp:~vila/bzr/316357-SIGWINCH

Due to popular demand (see https://bugs.launchpad.net/bugs/316357), I've put this patch up for review.

bzr will now listen to the SIGWINCH signal but it may reveal dormant bugs in parts of the code that don't yet handle EINTR.

Feedback and bug reports welcome: don't sit bored anymore watching the progress bar during those long test suite runs, shake your window size, that will shake the bzr code :)