Re: Odd merge behaviour involving reverts

> 
> On Thu, 18 Dec 2008, Alan wrote:
> > 
> > I think I know how to fix it.  I am just concerned about having it occur
> > again if someone else makes the same mistake I did.
> 
> I suspect we should warn about reverting merges. I'm surprised we don't 
> already. Reverting a merge isn't "wrong", but it's a whole lot more subtle 
> than reverting a regular commit.
> 
> Reverting a regular commit just effectively undoes what that commit did, 
> and is fairly straightforward. But reverting a merge commit also undoes 
> the _data_ that the commit changed, but it does absolutely nothing to the 
> effects on _history_ that the merge had.
> 
> So the merge will still exist, and it will still be seen as joining the 
> two branches together, and future merges will see that merge as the last 
> shared state - and the revert that reverted the merge brought in will not 
> affect that at all.
> 
> So a "revert" undoes the data changes, but it's very much _not_ an "undo" 
> in the sense that it doesn't undo the effects of a commit on the 
> repository history.
> 
> So if you think of "revert" as "undo", then you're going to always miss 
> this part of reverts. Yes, it undoes the data, but no, it doesn't undo 
> history.