$ hgcommit() {

  >    hg commit -u user "$@"

  > }

  $ hg init clhead

  $ cd clhead

  $ touch foo && hg add && hgcommit -m 'foo'

  adding foo

  $ touch bar && hg add && hgcommit -m 'bar'

  adding bar

  $ touch baz && hg add && hgcommit -m 'baz'

  adding baz

  $ echo "flub" > foo

  $ hgcommit -m "flub"

  $ echo "nub" > foo

  $ hgcommit -m "nub"

  $ hg up -C 2

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ echo "c1" > c1

  $ hg add c1

  $ hgcommit -m "c1"

  created new head

  $ echo "c2" > c1

  $ hgcommit -m "c2"

  $ hg up -C 2

  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo "d1" > d1

  $ hg add d1

  $ hgcommit -m "d1"

  created new head

  $ echo "d2" > d1

  $ hgcommit -m "d2"

  $ hg tag -l good

fail with three heads

  $ hg up -C good

  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg merge

  abort: branch 'default' has 3 heads - please merge with an explicit rev

  (run 'hg heads .' to see heads, specify rev with -r)

  [255]

close one of the heads

  $ hg up -C 6

  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ hgcommit -m 'close this head' --close-branch

succeed with two open heads

  $ hg up -C good

  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ hg up -C good

  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg merge

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

  $ hgcommit -m 'merged heads'

hg update -C 8

  $ hg update -C 8

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

hg branch some-branch

  $ hg branch some-branch

  marked working directory as branch some-branch

  (branches are permanent and global, did you want a bookmark?)

hg commit

  $ hgcommit -m 'started some-branch'

hg commit --close-branch

  $ hgcommit --close-branch -m 'closed some-branch'

hg update default

  $ hg update default

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

hg merge some-branch

  $ hg merge some-branch

  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  (branch merge, don't forget to commit)

hg commit (no reopening of some-branch)

  $ hgcommit -m 'merge with closed branch'

  $ cd ..