[PATCH] Correct show-diff output for deleted files

My convention is that contrary to files trimmed to zero size,
deleted files always go to /dev/null. This patch turns show-diff
to abide this.

Signed-off-by: Petr Baudis <pasky@ucw.cz>

show-diff.c

@@ -31,7 +31,7 @@ static void show_diff_empty(struct cache_entry *ce)
 		int c = 0;
 
 		printf("--- %s\n", ce->name);
-		printf("+++ %s\n", ce->name);
+		printf("+++ /dev/null\n");
 		p = old;
 		end = old + size; 
 		while (p < end)