On Fri, 2012-11-09 at 11:16:47 -0500, Jeff King wrote:
> On Fri, Nov 09, 2012 at 04:52:48PM +0100, Matthieu Moy wrote:
> 
> > Ulrich Spörlein <u...@spoerlein.net> writes:
> > 
> > >> > 2. Why the hell is the commit hash dependent on the ordering of the
> > >> > parent commits? IMHO it should sort the set of parents before
> > >> > calculating the hash ...
> > >> 
> > >> What would be the sort key?
> > >
> > > Trivially, the hash of the parents itself. So you'd always get
> > >
> > > ...
> > > parent 0000
> > > parent 1111
> > > parent aaaa
> > > parent ffff
> > 
> > That would change the behavior of --first-parent. Or you'd need to
> > compute the sha1 of the sorted list, but keep the unsorted one in the
> > commit. Possible, but weird ;-).
> 
> Right. The reason that merge parents are stored in the order given on
> the command line is not random or because it was not considered. It
> encodes a valuable piece of information: did the user merge "foo" into
> "bar", or did they merge "bar" into "foo"?
> 
> So I think this discussion is going in the wrong direction; git should
> never sort the parents, because the order is meaningful. The original
> complaint was that a run of svn2git produced different results on two
> different git versions. The important question to me is: did svn2git
> feed the parents to git in the same order?
> 
> If it did, and git produced different results, then that is a serious
> bug.
> 
> If it did not, then the issue needs to be resolved in svn2git (which
> _may_ want to sort the parents that it feeds to git, but it would depend
> on whether the order it is currently presenting is meaningful).

Yeah, thanks, looks like I have some more work to do. I don't quite get
how it could come up with a different order, seeing that it is using svn
as the base.

Will run some more experiments, thanks for the info so far.

Cheers,
Uli
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