Bugfix: Reset select list before rendering weather stations

ipmd/static/ipmd/js/ipmdlib.js

@@ -90,7 +90,7 @@ function getWeatherStationList(weatherDatasource){
 }
 
 function renderWeatherStationSelectList(stationList, selectList){
-
+    selectList.options.length = 0;
     selectList.add(new Option("-- Please select weather station --", -1));
     for(let i=0;i<stationList.length; i++)
     {