Don't use sed -r; instead use old-style regexp
Rev d895158fe8af introduced some sed -r tests, but -r is only available on GNU
sed, while BSD sed uses -E. Better to use old-style regular expressions, that
way the tests work on all sed variants.
#!/bin/sh
hg init a
cd a
hg init b
echo x > b/x
echo '# should print nothing'
hg add b
hg st
echo '# should fail'
hg st b/x
hg add b/x
echo '# should fail'
hg add b b/x
hg st
echo '# should arguably print nothing'
hg st b
echo a > a
hg ci -Ama a
echo '# should fail'
hg mv a b
hg st