[MERGE] Fix bug #235407, when the same revision is merged twice

[Martin Pool]

On Mon, Jun 2, 2008 at 1:41 PM, Robert Collins
<robertc at robertcollins.net> wrote:
> Robert Collins has voted reject.
> Status is now: Vetoed
> Comment:
> merge is definitely doing the wrong thing and should not be any harder to
> fix: there were tests at one point that add_parent_ids would normalise any
> new parents so only the heads were listed.

I believe it does have that check but --force bypasses it.  (I haven't
checked the code.)  If that's true I can't see any really good reason
to remove it and would support removing it.  If you can get there
without --force I'd agree that's a bug.

If we want to enforce it in another place you could make commit check
it, though I think at the moment it avoids scanning history and it
would be a shame to enforce it.

At any rate: having got a tree into this state, it is not very nice to
just leave the user with an error.

-- 
Martin <http://launchpad.net/~mbp/>