corrected ascii-art; Re: Disable backing out merges?

[Matt Mackall]

On Tue, 2011-10-11 at 02:30 -0500, Matt Mackall wrote:
> Again, it comes back to creating a future ambiguous merge ancestor.
> Introducing c' doesn't take c out of the graph, which means it may still
> end up being the basis for a future merge, thus reproducing the bad
> changes.

By the way, here's a proof of why once we have an ambiguous ancestor,
the problem is unsolvable:

http://mercurial.selenic.com/bts/msg10097

-- 
Mathematics is the supreme nostalgia of our time.