tests/narrow-library.sh

changegroup: always use the treemanifest-enabled version of _packmanifests()

It works for flat manifests too. We just cannot use cg1 or cg2 if we
have subdirectory manifests.

Differential Revision: https://phab.mercurial-scm.org/D4124

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