tests/narrow-library.sh

perf: fix some missing b prefixes

# skip-blame just b prefixes

Differential Revision: https://phab.mercurial-scm.org/D6457

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