Re: [PATCH] upload-pack: reject shallow requests that would return nothing

> Shallow clones with --shallow-since or --shalow-exclude work by
> running rev-list to get all reachable commits, then draw a boundary
> between reachable and unreachable and send "shallow" requests based on
> that.
>
> The code does miss one corner case: if rev-list returns nothing, we'll
> have no border and we'll send no shallow requests back to the client
> (i.e. no history cuts). This essentially means a full clone (or a full
> branch if the client requests just one branch). One example is the
> oldest commit is older than what is specified by --shallow-since.