AssignmentField clears filter applied after second picker show

[chuckn0rris]

Forum post

In advanced demo run in console

gantt.on('startCellEdit', (editorContext) => {
      if ( editorContext.editorContext.column.type == 'resourceassignment' ) {          
           editorContext.editorContext.editor.inputField.store.filter(record => (record.resource.name == 'George'));
      }
    });

Open cell editor for assignment column, open picker, see it's filtered. Close picker with combo btn, and show again. See list is not filtered anymore.