[PATCH] Avoid unnecessarily inflating and interpreting delta

This teaches packed_delta_info() that it only needs to look at
the type of the base object to figure out both type and size of
a deltified object.  This saves quite a many calls to inflate()
when dealing with a deep delta chain.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

cat-file.c

@@ -16,7 +16,8 @@ int main(int argc, char **argv)
 		usage("git-cat-file [-t | -s | tagname] <sha1>");
 
 	if (!strcmp("-t", argv[1]) || !strcmp("-s", argv[1])) {
-		if (!sha1_object_info(sha1, type, &size)) {
+		if (!sha1_object_info(sha1, type,
+				      argv[1][1] == 's' ? &size : NULL)) {
 			switch (argv[1][1]) {
 			case 't':
 				printf("%s\n", type);