From ebef31ffa5026f54dbc9cf960016efeb0a539c3e Mon Sep 17 00:00:00 2001
From: Pasi Kallinen <paxed@alt.org>
Date: Sat, 17 Nov 2018 19:48:48 +0200
Subject: [PATCH] Check monster relocation degenerate cases more strictly

Just in case we're trying to put the monster on the same location
where it already thinks it is... but actually isn't.
---
 src/mon.c      | 2 +-
 src/teleport.c | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/mon.c b/src/mon.c
index 7340e1ad6..232992d32 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -2586,7 +2586,7 @@ boolean move_other; /* make sure mtmp gets to x, y! so move m_at(x, y) */
     xchar newx, newy;
     coord mm;
 
-    if (mtmp->mx == x && mtmp->my == y)
+    if (mtmp->mx == x && mtmp->my == y && m_at(x,y) == mtmp)
         return TRUE;
 
     if (move_other && (othermon = m_at(x, y)) != 0) {
diff --git a/src/teleport.c b/src/teleport.c
index 9a6ff8f19..a7901e3d9 100644
--- a/src/teleport.c
+++ b/src/teleport.c
@@ -1005,8 +1005,8 @@ register int x, y;
     register int oldx = mtmp->mx, oldy = mtmp->my;
     boolean resident_shk = mtmp->isshk && inhishop(mtmp);
 
-    if (x == mtmp->mx && y == mtmp->my) /* that was easy */
-        return;
+    if (x == mtmp->mx && y == mtmp->my && m_at(x,y) == mtmp)
+        return; /* that was easy */
 
     if (oldx) { /* "pick up" monster */
         if (mtmp->wormno) {
-- 
2.40.0