tests: use $RUNTESTDIR instead of $TESTDIR in narrow-library.sh This is done so that third party extensions can use narrow-library.sh in tests. Differential Revision: https://phab.mercurial-scm.org/D5400

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