% manifest of p2:
bar
foo

created new head
% manifest of p1:
foo
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
% this should not mention bar:
changeset:   3:ef2fc9b4a51b
tag:         tip
parent:      2:ed1b79f46b9a
parent:      1:d394a8db219b
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
description:
merge


   rev    offset  length   base linkrev nodeid       p1           p2
     0         0       5      0       1 b004912a8510 000000000000 000000000000