Re: [PATCH 2/3] commit-graph: use the hash version byte

"brian m. carlson" [off-list ref] writes:

Can we maybe say something like this?

  switch (hash_algo_by_ptr(the_hash_algo)) {
    case GIT_HASH_SHA1:
      return 1;
    case GIT_HASH_SHA256:
      return 2;
    default:
      die(_("invalid hash version"));
  }

That way if SHA-256 gets broken and we switch to another 256-bit hash
(SHA-3-256?), we'll be forced to update this properly.

Excellent.