Grouping breaks Column Header Height for deferred columnDefs generation

http://plnkr.co/edit/u6LBOx?p=preview As you can see in this demo if the column header height is wrong when the grouping directive is added to the grid. This is only a problem when the column defs aren't there when the grid options are loaded. Example:

$timeout(function(){
  var newColumnDefs = [
    { name:'firstName', field: 'first-name', displayName: 'First Name'},
    { name:'1stFriend', field: 'friends[0]', displayName: '1st Friend'},
    { name:'city', field: 'address.city', displayName: 'City'},
    { name:'getZip', field: 'getZip()'}
  ];
  $scope.gridOptions.columnDefs = newColumnDefs;
}, 500);

This problem is not there for the grid without the grouping directive.

When you perform the grouping action the headers appear correctly however when you ungroup they return to their broken state. OS: Mac OSX Browser: Chrome Build: v3.0.0-rc.21-d68dcc6 - 2015-05-27