Fixed test-extdiff.
diff-like tools usually return 1 if differences are found.
Currently the extdiff returns 256, but that's a different topic
(consolidating return code handling in hg).
#!/bin/sh
mkdir t
cd t
hg init
echo import > port
hg add port
hg commit -m 0 -u spam -d '0 0'
echo export >> port
hg commit -m 1 -u eggs -d '1 0'
echo export > port
echo vaportight >> port
echo 'import/export' >> port
hg commit -m 2 -u spam -d '2 0'
echo 'import/export' >> port
hg commit -m 3 -u eggs -d '3 0'
head -n 3 port > port1
mv port1 port
hg commit -m 4 -u spam -d '4 0'
hg grep port port
hg grep --all -nu port port
hg grep import port
hg cp port port2
hg commit -m 4 -u spam -d '5 0'
echo '% follow'
hg grep -f 'import$' port2
echo deport >> port2
hg commit -m 5 -u eggs -d '6 0'
hg grep -f --all -nu port port2