From 00e504625f9a75bb2fe9ce66b06d055c559b66b4 Mon Sep 17 00:00:00 2001
From: Kevin Granade <kevin.granade@gmail.com>
Date: Sun, 17 Mar 2013 11:15:41 -0500
Subject: [PATCH] Prevent monsters with no path from following us down stairs.
 Fix contributed by Uronym.

---
 monmove.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/monmove.cpp b/monmove.cpp
index 0db99160accbe..36a2a71159a8d 100644
--- a/monmove.cpp
+++ b/monmove.cpp
@@ -766,6 +766,10 @@ bool monster::will_reach(game *g, int x, int y)
  if (has_flag(MF_IMMOBILE) && (posx != x || posy != y))
   return false;
 
+ std::vector<point> path = g->m.route(posx, posy, x, y, has_flag(MF_BASHES));
+ if (path.size() == 0)
+   return false;
+
  if (has_flag(MF_SMELLS) && g->scent(posx, posy) > 0 &&
      g->scent(x, y) > g->scent(posx, posy))
   return true;