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.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.