tests/narrow-library.sh

rust-dirstate-status: add call to rust-fast path for `dirstate.status`

The reasoning behind this patch is explained in the first patch of the series.

Differential Revision: https://phab.mercurial-scm.org/D7060

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