Re: Git 2.26 fetches many times more objects than it should, wasting gigabytes

> Thanks for the reproduction recipe (in [1]) and your analysis. I took a
> look, and it's because the check for in_vain is done differently. In v0:
> 
>   if (got_continue && MAX_IN_VAIN < in_vain) {
> 
> reflecting the documentation in pack-protocol.txt:
> 
>   However, the 256 limit *only* turns on in the canonical client
>   implementation if we have received at least one "ACK %s continue"
>   during a prior round.  This helps to ensure that at least one common
>   ancestor is found before we give up entirely.

> When debugging, I noticed that in_vain was increasing far in excess of
> MAX_IN_VAIN, but because got_continue was false, the client did not give
> up.
> 
> But in v2:
> 
>   if (!haves_added || *in_vain >= MAX_IN_VAIN) {
> 
> ("haves_added" is irrelevant to this discussion. It is another
> termination condition - when we have run out of "have"s to send.)
> 
> So there is no check that "continue" was sent. We probably should change
> v2 to match v0. I can start writing a patch unless someone else would
> like to take a further look at it.