(svn r7936) -Fix (r4987, old-rev): Only update the signals and YAPF cache on a DC_EXEC action for bridge-building

src/tunnelbridge_cmd.c

@@ -370,8 +370,11 @@ not_valid_below:;
 		}
 	}
 
-	SetSignalsOnBothDir(tile_start, AxisToTrack(direction));
-	YapfNotifyTrackLayoutChange(tile_start, AxisToTrack(direction));
+	if (flags & DC_EXEC) {
+		Axis axis = AxisToTrack(direction);
+		SetSignalsOnBothDir(tile_start, axis);
+		YapfNotifyTrackLayoutChange(tile_start, axis);
+	}
 
 	/* for human player that builds the bridge he gets a selection to choose from bridges (DC_QUERY_COST)
 	 * It's unnecessary to execute this command every time for every bridge. So it is done only