From 494c14427dd2854d928019558e1cf8f87ba30ca7 Mon Sep 17 00:00:00 2001
From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Wed, 4 Jan 2017 20:40:08 +0100
Subject: [PATCH] Fix ICS Crazyhouse play

The new way to associate promoted partners to pieces had woken up a latent
bug in the code that determined whether pieces in the ICS board are promoted
Pawns. This led to Pawns appearing out of nowhere on squares evacuated by
white Pawns.
---
 backend.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/backend.c b/backend.c
index b7f36b2..7cc8f9c 100644
--- a/backend.c
+++ b/backend.c
@@ -4907,7 +4907,7 @@ ParseBoard12 (char *string)
                && gameInfo.variant != VariantGrand&& gameInfo.variant != VariantSChess) // inherit info that ICS does not give from previous board
               for(k=0; k<ranks; k++) for(j=BOARD_LEFT; j<BOARD_RGHT; j++) {
                 ChessSquare old, new = boards[moveNum][k][j];
-                  if(fromY == DROP_RANK && k==toY && j==toX) continue; // dropped pieces always stand for themselves
+                  if(new == EmptySquare || fromY == DROP_RANK && k==toY && j==toX) continue; // dropped pieces always stand for themselves
                   old = (k==toY && j==toX) ? boards[moveNum-1][fromY][fromX] : boards[moveNum-1][k][j]; // trace back mover
                   if(old == new) continue;
                   if(old == PROMOTED(new)) boards[moveNum][k][j] = old;// prevent promoted pieces to revert to primordial ones
@@ -4915,7 +4915,7 @@ ParseBoard12 (char *string)
                       if(old < WhiteCannon || old >= BlackPawn && old < BlackCannon)
                            boards[moveNum][k][j] = PROMOTED(old); // choose correct type of Gold in promotion
                       else boards[moveNum][k][j] = old; // preserve type of Gold
-                  } else if((old == WhitePawn || old == BlackPawn) && new != EmptySquare) // Pawn promotions (but not e.p.capture!)
+                  } else if(old == WhitePawn || old == BlackPawn) // Pawn promotions (but not e.p.capture!)
                       boards[moveNum][k][j] = PROMOTED(new); // use non-primordial representation of chosen piece
               }
 	  } else {
-- 
1.7.0.4