Fix "git diff blob1 blob2" showing the diff in reverse.

This was introduced by mistake when revision.c::add_pending_object()
was modified to use object-array instead of object-list.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/builtin-diff.c b/builtin-diff.c
index 48d2fd0..ec27542 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c
@@ -125,9 +125,6 @@
 			      int argc, const char **argv,
 			      struct blobinfo *blob)
 {
-	/* Blobs: the arguments are reversed when setup_revisions()
-	 * picked them up.
-	 */
 	unsigned mode = canon_mode(S_IFREG | 0644);
 
 	if (argc > 1)
@@ -135,7 +132,7 @@
 
 	stuff_change(&revs->diffopt,
 		     mode, mode,
-		     blob[1].sha1, blob[0].sha1,
+		     blob[0].sha1, blob[1].sha1,
 		     blob[0].name, blob[0].name);
 	diffcore_std(&revs->diffopt);
 	diff_flush(&revs->diffopt);