Show both blob names from "git diff blob1 blob2"

Earlier we deliberately showed only blob1's name because showing
both names labeled the output as a renaming patch.  Now the output
routine (namely, diff.c::resolve_rename_copy()) is taught not to
use pathname comparison to tell if a filepair is a rename, we can
safely do this change.

Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-diff.c

@@ -133,7 +133,7 @@ static int builtin_diff_blobs(struct rev_info *revs,
 	stuff_change(&revs->diffopt,
 		     mode, mode,
 		     blob[0].sha1, blob[1].sha1,
-		     blob[0].name, blob[0].name);
+		     blob[0].name, blob[1].name);
 	diffcore_std(&revs->diffopt);
 	diff_flush(&revs->diffopt);
 	return 0;