Inconsistent insertion in QSortFilterProxyModel

I use QSortFilterProxyModel in QComboBox with insertPolicy = InsertAtBottom. I fill the model of 2 rows: the first one will be filtered and the second row is OK. So the combobox list of items contains one row.  After insertion a new item I get the empty first row (instead of the old item) and the new item in the second row (it's OK).

The bug is in QSortFilterProxyModel::insertRows method, in lines:

int source_row = (row >= m->source_rows.count()
    ? m->source_rows.count()
    : m->source_rows.at(row));

must be:

int source_row = (row >= m->source_rows.count()
    ? m->proxy_rows.count()
    : m->source_rows.at(row));

That is because later in QSortFilterProxyModelPrivate::source_items_inserted method there is a line: 

source_to_proxy.insert(start, delta_item_count, -1);

Here start is source_row of previous code (that is m->source_rows.count()) and source_to_proxy is m->proxy_rows.

So, in my example, in my source model, there will be inserted an empty item at index position 1 (instead of 2), and then there will be changed Qt::DisplayRole data at index position 2.