bdiff: normalize the diff (issue1295)
When the common part of a diff can be moved forward, move it forward.
Otherwise we don't get deterministic results (it would depends on the way we
split for the recursion).
That way we get identical hunks when doing the same change, it helps to solve
issue1295 (inconsistent diffs on different side during a merge).
% init
% no working directory
% setup
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
% hg children at revision 3 (tip)
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
% hg children at nullrev (should be 0 and 3)
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg children at revision 1 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% hg children at revision 2 (other head)
% hg children -r null
changeset: 0:4df8521a7374
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 3:e2962852269d
tag: tip
parent: -1:000000000000
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: 3
% hg children -r 0
changeset: 1:708c093edef0
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: 1
% hg children -r 1
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
% hg children -r 2
% hg children -r 3
% hg children -r 0 file0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
% hg children -r 1 file0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
% hg children file0 at revision 0 (should be 2)
changeset: 2:8f5eea5023c2
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: 2