(svn r25037) -Fix [FS#5480]: green path signals would be shown when building them 'under' a train, and they would keep showing green until they were passed again

src/rail_cmd.cpp

@@ -1139,9 +1139,9 @@ CommandCost CmdBuildSingleSignal(TileIndex tile, DoCommandFlag flags, uint32 p1,
 		DirtyCompanyInfrastructureWindows(GetTileOwner(tile));
 
 		if (IsPbsSignal(sigtype)) {
-			/* PBS signals should show red unless they are on a reservation. */
+			/* PBS signals should show red unless they are on reserved tiles without a train. */
 			uint mask = GetPresentSignals(tile) & SignalOnTrack(track);
-			SetSignalStates(tile, (GetSignalStates(tile) & ~mask) | ((HasBit(GetRailReservationTrackBits(tile), track) ? UINT_MAX : 0) & mask));
+			SetSignalStates(tile, (GetSignalStates(tile) & ~mask) | ((HasBit(GetRailReservationTrackBits(tile), track) && EnsureNoVehicleOnGround(tile).Succeeded() ? UINT_MAX : 0) & mask));
 		}
 		MarkTileDirtyByTile(tile);
 		AddTrackToSignalBuffer(tile, track, _current_company);