tests/test-diff-reverse

commands: get rid of generic exception in debugbuilddag

#!/bin/sh

hg init
cat > a <<EOF
a
b
c
EOF
hg ci -Am adda

cat > a <<EOF
d
e
f
EOF
hg ci -m moda

hg diff --reverse -r0 -r1

cat >> a <<EOF
g
h
EOF
hg diff --reverse --nodates