--- a/src/economy.cpp	Fri Apr 25 19:27:27 2008 +0000
+++ b/src/economy.cpp	Sat Apr 26 20:54:56 2008 +0000
@@ -45,6 +45,7 @@
 #include "rail_map.h"
 #include "signal_func.h"
 #include "gfx_func.h"
+#include "autoreplace_func.h"
 
 #include "table/strings.h"
 #include "table/sprites.h"
@@ -455,6 +456,19 @@
 		UpdateSignalsInBuffer();
 	}
 
+	/* In all cases clear replace engine rules.
+	 * Even if it was copied, it could interfere with new owner's rules */
+	RemoveAllEngineReplacementForPlayer(GetPlayer(old_player));
+
+	if (new_player == PLAYER_SPECTATOR) {
+		RemoveAllGroupsForPlayer(old_player);
+	} else {
+		Group *g;
+		FOR_ALL_GROUPS(g) {
+			if (g->owner == old_player) g->owner = new_player;
+		}
+	}
+
 	/* Change color of existing windows */
 	if (new_player != PLAYER_SPECTATOR) ChangeWindowOwner(old_player, new_player);