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 repo
cd repo
echo line 1 > foo
hg ci -qAm 'add foo' -d "1000000 0"
# copy foo to bar and change both files
hg cp foo bar
echo line 2-1 >> foo
echo line 2-2 >> bar
hg ci -m 'cp foo bar; change both' -d "1000000 0"
# in another branch, change foo in a way that doesn't conflict with
# the other changes
hg up -qC 0
echo line 0 >| foo
hg cat foo >> foo
hg ci -m 'change foo' -d "1000000 0"
# we get conflicts that shouldn't be there
hg merge --debug
echo "-- foo --"
cat foo
echo "-- bar --"
cat bar