commandserver: do not set nontty flag if channel is replaced by a real file This prepares for porting the chg server. In chg, a server receives client's stdio over a UNIX domain socket to override server channels. This is because chg should behave as if it is a normal hg command attached to tty. "nontty" is not wanted. This patch is corresponding to the following change. This doesn't test the identity of "cin" object because the current version of chg reopens stdio to apply buffering mode. https://bitbucket.org/yuja/chg/commits/c48c7aed5fc0