tests/narrow-library.sh

sshpeer: don't read(0)

read(0) is essentially a no-op. Let's avoid the function call, overhead,
and extra test output by not performing it.

Differential Revision: https://phab.mercurial-scm.org/D2581

cat >> $HGRCPATH <<EOF
[extensions]
narrow=
[ui]
ssh=python "$TESTDIR/dummyssh"
[experimental]
changegroup3 = True
EOF