http://mercurial.selenic.com/bts/issue1877 $ hg init a $ cd a $ echo a > a $ hg add a $ hg ci -m 'a' $ echo b > a $ hg ci -m'b' $ hg up 0 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg book main $ hg book * main 0:cb9a9f314b8b $ echo c > c $ hg add c $ hg ci -m'c' created new head $ hg book * main 2:d36c0562f908 $ hg heads changeset: 2:d36c0562f908 bookmark: main tag: tip parent: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c changeset: 1:1e6c11564562 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b $ hg up 1e6c11564562 1 files updated, 0 files merged, 1 files removed, 0 files unresolved $ hg merge main 1 files updated, 0 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) $ hg book main 2:d36c0562f908 $ hg ci -m'merge' $ hg book main 2:d36c0562f908