ui: look before you leap on sys.stderr.closed (and look nicer)
f83291e5643e introduced a fix if sys.stdout.closed does not exist.
This change uses a getattr with default instead of hasattr (which just calls
getattr) and accessing the attribute.
Additionally it applies the same fix for sys.stderr.closed as this is not
available in the bpython shell (reported by Roger Gammans).
#!/bin/sh
echo % setting up repo
hg init test
cd test
echo a > a
hg ci -Ama
hg rm a
hg ci -mdel
echo % set up hgweb
hg serve -n test -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
cat hg.pid >> $DAEMON_PIDS
echo % revision
"$TESTDIR/get-with-headers.py" localhost:$HGPORT '/rev/tip'
echo % diff removed file
"$TESTDIR/get-with-headers.py" localhost:$HGPORT '/diff/tip/a'