ed: Treat addresses of 0 as 1 for insert

From 6665eaa1d2c25a95b44a4f4fb3d24a3bd5c1180f Mon Sep 17 00:00:00 2001
From: Thomas Mannay <audiobarrier@openmailbox.org>
Date: Thu, 3 Nov 2016 15:16:32 +0000
Subject: [PATCH] Treat addresses of 0 as 1 for insert
diff --git a/ed.c b/ed.c
index 72248ab..52b2684 100644
--- a/ed.c
+++ b/ed.c
@@ -1143,7 +1143,7 @@
 		chkprint(1);
 		deflines(curln, curln);
 		if (!line1)
-			goto bad_address;
+			line1++;
 		append(prevln(line1));
 		break;
 	case 'a':