fix(stacks): check for editor change before setting as dirty

app/portainer/views/stacks/edit/stackController.js

@@ -203,10 +203,9 @@ angular.module('portainer.app').controller('StackController', [
     $scope.editorUpdate = function (cm) {
       if ($scope.stackFileContent !== cm.getValue()) {
         $scope.state.isEditorDirty = true;
+        $scope.stackFileContent = cm.getValue();
+        $scope.state.yamlError = StackHelper.validateYAML($scope.stackFileContent, $scope.containerNames);
       }
-      $scope.stackFileContent = cm.getValue();
-      $scope.state.yamlError = StackHelper.validateYAML($scope.stackFileContent, $scope.containerNames);
-      $scope.state.isEditorDirty = true;
     };
 
     $scope.stopStack = stopStack;