Re: [PATCH 3/7] commit-graph: start parsing generation v2 (again)

>> I am wondering if there is some notion of "if you do not understand
>> what this chunk is, you are incapable of handling this file
>> correctly, so do not use it" kind of bit per chunks (similar to the
>> index extensions where ones that begin with [A-Z] are optional) that
>> may negatively affect this plan.
>
> The chunk IDs do not have this special casing rule. This is a
> bit unfortunate for certain cases like adding something that _must_
> be understood. Here, it works to our benefit that GDAT and GDOV are
> optional and can be safely ignored. Thus, clients with this patch
> will ignore GDAT and GDOV and continue using topological levels
> form the CDAT chunk. Older clients without this patch will ignore
> the new GDA2 and GDO2 chunks and continue using topological levels.
>
> For Git versions without this topic branch, this "continue using
> topological levels" means no change of behavior at all.