From 7e72bc0944491c4d6b3d0094f488722ea558ca07 Mon Sep 17 00:00:00 2001
From: Bart House <bart@barthouse.com>
Date: Sat, 6 Jul 2019 14:18:02 -0700
Subject: [PATCH] mklev() set xxstairs_room pointers back to NULL upon
 completion.

When mklev() is called multiple times, previous state stored in the
xxstairs_room pointers can be mistakenly used when making decisions about
the new level being constructed.  This caused non-deterministic level
creation behavior when replaying from a snapshot.
---
 src/mklev.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/mklev.c b/src/mklev.c
index 525e0a58e..10f019f82 100644
--- a/src/mklev.c
+++ b/src/mklev.c
@@ -1016,6 +1016,10 @@ mklev()
     for (ridx = 0; ridx < SIZE(rooms); ridx++)
         rooms[ridx].orig_rtype = rooms[ridx].rtype;
 
+    dnstairs_room = NULL;
+    upstairs_room = NULL;
+    sstairs_room = NULL;
+
     reseed_random(rn2);
     reseed_random(rn2_on_display_rng);
 }