Merging with ancestor and DAG well-formedness

Matt Mackall mpm at
Sun Dec 26 12:50:34 CST 2010

On Sun, 2010-12-26 at 01:26 +0100, Mads Kiilerich wrote:
> Please share your opinion here or comment on 
> .
> Is it an implicit invariant in the Mercurial repository data model that 
> a merge always merges changesets that not are each others 
> ancestor/descendant? Or is it only something that mostly is enforced at 
> the command line API?

It is at best meaningless and at worst, likely to provoke suboptimal
answers from future ancestor calculations by skewing the 'distance from
root' metric. So it's not useful or desirable, but it's only mildly
problematic for the core algorithms.

Mathematics is the supreme nostalgia of our time.

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