ancestor: optimize _lazyancestorsiter() for contiguous chains
If there's no revision between p1 and current, p1 must be the next revision
to visit. In this case, we can get around the overhead of heappop/push
operations. Note that this is faster than using heapreplace().
'current - p1 == 1' could be generalized as 'all(r not in seen for r in
xrange(p1, current)', but Python is too slow to do such thing.
running: init test1
result: 0
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: 0
running: commit -m commit2 -d 2000-01-02 foo
result: 0
running: log -r 0
changeset: 0:0e4634943879
user: test
date: Sat Jan 01 00:00:00 2000 +0000
summary: commit1
result: 0
running: log -r tip
changeset: 1:45589e459b2e
tag: tip
user: test
date: Sun Jan 02 00:00:00 2000 +0000
summary: commit2
result: 0