tests/narrow-library.sh

py3: make tests/test-log-linerange.t work on Python 3

Made sure we write bytes to file and we suppress the return value of open().

Differential Revision: https://phab.mercurial-scm.org/D2893

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