tests/narrow-library.sh

tests: add b prefixes to test-hg-parseurl.py

Now passes on Python 3.

Differential Revision: https://phab.mercurial-scm.org/D3374

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