http-push: use hex_to_bytes()

The path of a loose object contains its hash value encoded into two
substrings of hexadecimal digits, separated by a slash.  The current
code copies the pieces into a temporary buffer to get rid of the slash
and then uses get_oid_hex() to decode the hash value.

Avoid the copy by using hex_to_bytes() directly on the substrings.
That's shorter and easier.

While at it correct the length of the second substring in a comment.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -1007,20 +1007,18 @@ static void remote_ls(const char *path, int flags,
 		      void (*userFunc)(struct remote_ls_ctx *ls),
 		      void *userData);
 
-/* extract hex from sharded "xx/x{40}" filename */
+/* extract hex from sharded "xx/x{38}" filename */
 static int get_oid_hex_from_objpath(const char *path, struct object_id *oid)
 {
-	char hex[GIT_MAX_HEXSZ];
-
 	if (strlen(path) != GIT_SHA1_HEXSZ + 1)
 		return -1;
 
-	memcpy(hex, path, 2);
+	if (hex_to_bytes(oid->hash, path, 1))
+		return -1;
 	path += 2;
 	path++; /* skip '/' */
-	memcpy(hex + 2, path, GIT_SHA1_HEXSZ - 2);
 
-	return get_oid_hex(hex, oid);
+	return hex_to_bytes(oid->hash + 1, path, GIT_SHA1_RAWSZ - 1);
 }
 
 static void process_ls_object(struct remote_ls_ctx *ls)