Disable backing out merges?

[Dominik Psenner]

>> Maybe what we need is not a way to fix a broken merge but a way to
>> tell users and mercurial that they should not _use_ that broken merge?
>
>I suppose you could achieve this via closing the line of development
>following the merge, and then add a hook which prevented adding new
>changesets that derive from such a line. Unless, perhaps, such changesets
>contain a magic string - "reopens X" or something similar. You'd probably
>want to add a bit of bookkeeping to prevent it from being slow, so it might
>make better sense as an extension.

Maybe there should be some kind of branch flag like "broken" that is alike
"closed". hg could disallow to commit a new changeset if one of it's parents
would be marked as "broken". In a way it is just stronger than "closed", but
behaves similar.