sshserver: do setbinary() by caller (API)
In most cases, stdio should be set to binary mode by the dispatcher, so
the sshserver does not have to take care of that. The only exception was
hg-ssh, which is fixed by this patch.
.. api::
``sshserver()`` no longer sets stdin and stdout to binary mode.
#if no-windows no-osx
$ mkdir -p xdgconf/hg
$ echo '[ui]' > xdgconf/hg/hgrc
$ echo 'username = foobar' >> xdgconf/hg/hgrc
$ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
$ unset HGRCPATH
$ hg config ui.username 2>/dev/null
foobar
#endif