Fixed small issue when changing data source from metrics panel

src/app/features/panel/panelSrv.js

@@ -58,13 +58,7 @@ function (angular, _, config) {
 
       $scope.setDatasource = function(datasource) {
         $scope.panel.datasource = datasource;
-        datasourceSrv.get(datasource).then(function(ds) {
-          $scope.datasource = ds;
-        });
-      };
-
-      $scope.changeDatasource = function(datasource) {
-        $scope.setDatasource(datasource);
+        $scope.datasource = null;
         $scope.get_data();
       };
 

src/app/partials/metrics.html

@@ -15,7 +15,7 @@
 
     <ul class="dropdown-menu" role="menu">
       <li ng-repeat="datasource in datasources" role="menuitem">
-        <a ng-click="changeDatasource(datasource.value);">{{datasource.name}}</a>
+        <a ng-click="setDatasource(datasource.value);">{{datasource.name}}</a>
       </li>
     </ul>
   </div>