tests/narrow-library.sh

changelog: also monitor `00changelog.n` when applicable (issue6554)

This let the locarepo's file cache detect outdated nodemap docket and reload the
changelog after `localrepo.invalidate` when applicable.

Differential Revision: https://phab.mercurial-scm.org/D11482

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