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Re: Strange behavior of git rev-list




Thanks. Any plans to fix that? Or is there a way to turn off this heuristic?

On 7 September 2017 at 11:47, Jeff King <peff@xxxxxxxx> wrote:
> On Thu, Sep 07, 2017 at 11:20:15AM +0200, Paweł Marczewski wrote:
>
>> I have an interesting case. In my repository, there are two commits,
>> 'one' and 'two'. 'one' is reachable from 'two' (as evidenced by 'git
>> rev-list two | grep $(giv rev-parse one)'). However, the output of
>> 'git rev-list two..one' is not empty, as is 'git rev-list ^two one'.
>>
>> Here is the repository: https://github.com/pwmarcz/git-wtf/
>>
>> It seems that the commit dates influence this behavior, because when I
>> edit all the dates to be the same, the output of 'git rev-list
>> two..one' is empty. Pruning seemingly irrelevant parents also makes it
>> empty.
>>
>> I verified the behavior on git versions 2.14.1, 2.11.0, and on the
>> 'next' branch (2.14.1.586.g1a2e63c10).
>
> Yes, this is known. The commit dates are used as a proxy for graph
> height (or generation numbers, if you prefer) so that we avoid having to
> walk all the way down to a merge base before producing any output. But
> it can give the wrong answer in the face of clock skew.
>
> We walk back five extra commits more than we need to in order to avoid
> small runs of skewed commits, but obviously you can have arbitrary-sized
> runs.
>
> -Peff