Reverse the way backout is doing the merge

[Peter Arrenbrecht]

On Thu, Feb 21, 2008 at 11:15 AM, Martin Sjögren
<martin.sjogren at jasper-da.com> wrote:
> tor 2008-02-21 klockan 10:35 +0100 skrev Peter Arrenbrecht:
>
> > I believe this proposal is related to
>  >
>  >   http://www.venge.net/mtn-wiki/DaggyFixes
>  >
>  > The current behaviour seems to be daggy, the proposed one not. From a
>  > theoretical point of view I would prefer the daggy behaviour. However,
>  > I have no practical experience with backout, so I cannot comment on
>  > its actual usability.
>
>  If I understand correctly, the diffs you see in a merge changeset is
>  towards the "first" child node, which is somewhat arbitrary, and what
>  the proposed change does is swap which is the "first" child in the merge
>  between the backout changeset and whatever you're merging with.
>
>  If I've understood correctly :-) this sounds like a good change, making
>  the diff from merging in a backout changeset more intuitive.

So do I understand correctly that the current behaviour when undoing B
in A -> B -> C -> D is:

A -> B --> C -> D --> E
       \          /
        -> !B --->

where the first parent of E is D and the proposed change simply
switches parents for E but leaves the layout of the DAG as is? If so,
then fine with me.

>  I can't see how you could end up with a history that's NOT a dag
>  (directed acyclic graph), wouldn't that be rather impossible?

Sure. The point was what the DAG looks like.
-peo