[PATCH 4 of 6 V2] merge: include obsolete calculation for branchtips

[Sean Farley]

pierre-yves.david at ens-lyon.org writes:

> On 01/12/2014 02:25 PM, Sean Farley wrote:
>> Tests will be updated in the next patch because it requires a non-obvious fix
>> to the test case.
> Do you mean test are failing? or just that some of the changes in this 
> commit are not tested ?

I meant that the tests are currently wrong and that this patch fixes the
wrongness of the tests but that the change required should go into
another patch.

> Why can't you put them in this changeset ?

They could be folded into one patch if that's what people want. I
originally thought it'd be easier to review.