Thanks @ all for clarifying this mystery, this already helped a lot to 
figure out what's going on there.

Even though the affected commit objects are malformed, it would be very 
helpful if this problem could be solved somehow, from a user 
perspective. Such malformed objects can potentially occur also in other 
comparably old projects, where searching for commits that have been made 
in a specific time window in the past could be useful or even necessary 
in some cases.

On the other hand, if it would be a huge effort to solve the problem 
(which I cannot assess), I could fully understand that it might not be 
worth to completely fix this specific problem that occurs only in few 
cases in the past (if you are sure that such malformed objects cannot 
occur any more today). If you decide to not spend the effort on fixing 
this problem, however, I would appreciate if you could, at least, 
partially fix this problem by not treating the broken commit objects to 
be before any other commit object (timestamp 0), but introduce some kind 
of error handling for such commits that omits listing them in the wrong 
time period.

Thanks again for all the explanations and thoughts!

Best,
Thomas

Am 18.04.23 um 16:02 schrieb Derrick Stolee:
> On 4/18/2023 12:12 AM, Jeff King wrote:
>
>> One thing the commit graph perhaps _could_ do is omit the commit, or
>> mark it as "this one is broken in some way". And then fall back to
>> parsing those few instead (which is slower, but if it's a small minority
>> of commits, that's OK). But I don't think there's any code for that.
> The "broken" commit would need to be included in the commit-graph file
> so its children can point to it using a graph position, but then it
> would revert to parsing from the commit object (due to some new concept
> storing "this is a bad commit").
>
> If we decided to treat a timestamp of 0 as "probably broken, artificial
> at best" then we wouldn't need the new indicator in the commit-graph
> file, but this seems like quite a big hammer for a small case.
>
> Thanks,
> -Stolee