tests/test-diff-hashes

deltaparent(): don't return nullrev for a revision containing a full snapshot

this allows us to simplify manifest.readdelta and revlog.revdiff

#!/bin/sh

hg init a
cd a
hg diff not found
echo bar > foo
hg add foo
hg ci -m 'add foo' -d '1000000 0'

echo foobar > foo
hg ci -m 'change foo' -d '1000001 0'

echo 'quiet:'
hg --quiet diff -r 0 -r 1
echo

echo 'normal:'
hg diff -r 0 -r 1
echo

echo 'verbose:'
hg --verbose diff -r 0 -r 1
echo

echo 'debug:'
hg --debug diff -r 0 -r 1
echo