make ui flush output. this makes error happen if printing to /dev/full.
before this change, error happened with some pythons, but not others.
now always happens.
fixes issue 155.
Metadata-Version: 1.0
Name: mercurial
Version: 0.7
Summary: scalable distributed SCM
Home-page: http://selenic.com/mercurial
Author: Matt Mackall
Author-email: mpm@selenic.com
License: GNU GPL
Description: UNKNOWN
Platform: UNKNOWN