ui: also swap sys.stdout with self.fout in _readline
In
17ffb30d9174, _readline was changed to output a space using
raw_input and this was done using sys.stdout directly, not self.fout.
This change broke the command server for JavaHg since it (and other
clients) would see a spurious ' ' on stdout and interpret this as an
unknown channel.
$ "$TESTDIR/hghave" inotify || exit 80
$ hg init
$ echo "[extensions]" > .hg/hgrc
$ echo "inotify=" >> .hg/hgrc
$ hg inserve -d --pid-file .hg/inotify.pid
$ echo a > a
$ hg ci -Aqm0
$ hg co -q null
$ hg co -q
$ hg st
$ cat a
a
$ kill `cat .hg/inotify.pid`