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
HGRCPATH=$HGTMP/.hgrc; export HGRCPATH
echo "[extensions]" >> $HGTMP/.hgrc
echo "extdiff=" >> $HGTMP/.hgrc
hg init a
cd a
echo a > a
hg add
hg extdiff -o -Nr
echo "[extdiff]" >> $HGTMP/.hgrc
echo "cmd.falabala=echo" >> $HGTMP/.hgrc
echo "opts.falabala=diffing" >> $HGTMP/.hgrc
hg falabala
hg help falabala
hg ci -d '0 0' -mtest1
echo b >> a
hg ci -d '1 0' -mtest2
hg falabala -r 0:1 || echo "diff-like tools yield a non-zero exit code"