git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
hdr.hdr_entries = htonl(object_count);
git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
hdr.hdr_entries = htonl(object_count);
git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));