Re: [Monotone-devel] Bogus merge with 0.38

[Julio M. Merino Vidal]

On Feb 4, 2008, at 12:51 AM, William Uther wrote:
> That error message was introduced is revision  
> a71b546a834a4ac9561d57e9747e69312c1a6b80
>
> It is a recent change.  The code is in the insert_if_unborn()  
> function in roster_merge.cc.
>
> insert_if_unborn() is used to add a node to the new revision of a  
> merge if it only exists on
> one side of the merge.  The new code is inserted in the  
> if_not_unborn side of the if_unborn if
> statement.  There used to be nothing there - the node was dropped  
> because of die-die-die merge.
>
> The new code simply outputs the warning you see.  The revisions  
> listed are the content marks on
> the file that are in the uncommon ancestor set.
>
> This raises a few questions...
>
> i) Why does monotone think the file subrs/atf.config.subr.in has  
> been deleted on one side of the merge?  Had it been?  If not, had  
> it been added on only one side of the merge?

Yes, it was deleted on one side.  And the merge in this case was  
correct due to the "Die, die, die" policy.

> ii) Why is revision 0000000000000000000000000000000000000004 in  
> both the marks of the file and the uncommon ancestor set?  I assume  
> this is a bogus revision ID?  (It is technically vaild, just...  
> unlikely.  Can you mtn log --from 0000...0004?)

It's not there with log.  But the other reply in the thread explains it.

> Something weird is going on.  I find it hard to see how that change  
> could have broken anything - but it is revealing something weird  
> going on in the uncommon ancestor set and content marks.
>
> I don't suppose this is repeatable?  i.e. If you run mtn diff can  
> you get a diff of your changes from a known revision.  Then check  
> out fresh working copies, use patch to apply your changes, and then  
> see if you can repeat the whole mess.

I was able to reproduce the configure.ac bad merge quite easily in a  
clean database with a custom file.  I can add a test for it in the  
test suite (obviously failing for now).