narrow: drop server support for widening using the getbundle command (BC)
The client still supports widening using the getbundle, which we
(Google) still depend on a for a little while more (we've started the
migration to the new narrow_widen command, but we're not done yet).
Differential Revision: https://phab.mercurial-scm.org/D7093
cat >> $HGRCPATH <<EOF
[extensions]
narrow=
[ui]
ssh=python "$RUNTESTDIR/dummyssh"
[experimental]
changegroup3 = True
EOF