simplemerge: flush stdout before writing to stderr.
Besides, stderr is not always unbuffered under win32 (when redirections occur for instance), and it should be flushed too.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
See http://www.selenic.com/mercurial/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.