merge: fix a copy detection bug (issue672) When merging rev1 and rev2, we want to search for copies that happened in rev1 but not in rev2 and vice-versa. We were starting the search at rev1/rev2 and then going back, stopping as soon as we reached the revno of the ancestor, but that can miss some cases (see the new test-issue672). Now we calculate the revisions that are ancestors of rev1 or rev2 (but not both) and make sure the search doesn't stop too early. Simplified test provided by mpm, based on a test case provided by Edward Lee.

#!/bin/sh

hg init

mkdir alpha
touch alpha/one
mkdir beta
touch beta/two

hg add alpha/one beta/two
hg ci -m "start" -d "1000000 0"

echo 1 > alpha/one
echo 2 > beta/two

echo EVERYTHING
hg diff --nodates

echo BETA ONLY
hg diff --nodates beta

echo INSIDE BETA
cd beta
hg diff --nodates .