Fixed thief's back sliding animation

Fixed #1914

Thanks to @zackdreaver for reporting and @aleos89 for his help!

src/map/skill.c

@@ -8010,8 +8010,9 @@ int skill_castend_nodamage_id (struct block_list *src, struct block_list *bl, ui
 		break;
 
 	case TF_BACKSLIDING: //This is the correct implementation as per packet logging information. [Skotlex]
-		if (skill_blown(src,bl,skill_get_blewcount(skill_id,skill_lv),unit_getdir(bl),BLOWN_IGNORE_NO_KNOCKBACK))
-			clif_skill_nodamage(src, bl, skill_id, skill_lv, 1);
+		skill_blown(src,bl,skill_get_blewcount(skill_id,skill_lv),unit_getdir(bl),BLOWN_IGNORE_NO_KNOCKBACK|BLOWN_DONT_SEND_PACKET);
+		clif_skill_nodamage(src, bl, skill_id, skill_lv, 1);
+		clif_blown(src); // Always blow, otherwise it shows a casting animation. [Lemongrass]
 		break;
 
 	case TK_HIGHJUMP: