Mercurial でセントラルリポジトリのマルチプルヘッドを禁止する

@  2:d9ae2b51cade | head b
|  default
|
| o  1:8141de67f6ee | head a
|/   default
|
o  0:6af850d9f57f | initial commit
   default
図1. defaultブランチがマルチプルヘッド(先端(HEAD)が複数存在している状態)

[troter:~/tmp/multiple-head]
% hg push
pushing to /home/troter/tmp/central
searching for changes
abort: push creates new remote head 8141de67f6ee!
(did you forget to merge? use push -f to force)
[troter:~/tmp/multiple-head]
% hg push -f
pushing to /home/troter/tmp/central
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files (+1 heads)
[troter:~/tmp/multiple-head]
%

[hooks]
pretxnchangegroup.forceonehead = /path/to/force-one-head

[hooks]
pretxnchangegroup.forceonehead = .hg/force-one-head

    [troter:~/tmp/multiple-head]
    % hg push -f
    pushing to /home/trote/tmp/central
    searching for changes
    adding changesets
    adding manifests
    adding file changes
    added 2 changesets with 2 changes to 2 files (+1 heads)
    There are multiple heads.
    Please 'hg pull' and get your repository up to date first.
    Also, don't 'hg push --force' because that won't work either.
    transaction abort!
    rollback completed
    abort: pretxnchangegroup.forceonehead hook exited with status 1
    [troter:~/tmp/multiple-head]
    %