After dispatch, without chg we have handling of flushing of streams and
exception handling related to it. The exception handling part is important
because there can be exceptions when flushing fout or ferr.
One such case is in test-basic.t which was failing on python3+chg without this
patch as this handling was missing from chg.
Failure can be seen at
Honestly I am not sure which one of chgserver.py or commandserver.py the
change should go in.