Is a tree item its own sibling?

I have a routine that takes a tree item selected by a user and loops through all of the item's siblings:

itemRelated = TRUE;
treeItemToTest = 0;

while ((itemRelated) && (treeItemToTest < totalTreeItems) && 
    (treeItemToTest >= 0))
{
    /* Check if file is related to the selected file */
    AreTreeItemsRelated(panelHandle, treeHandle, 
        treeItemToTest, VAL_SIBLING, selectedTreeIndex,&itemRelated);
    if (itemRelated)
    {
        /* process the item */
        /* ... */

        ++treeItemToTest;
    }
}    

Somewhere in between CVI 2012 and the current version, our program stopped working correctly.  I traced the problem to the AreTreeItemsRelated call in this routine.  In the latest version of LabWindows, this call will return FALSE if treeItemToTest and selectedTreeIndex are the same item.  This is apparently a change in behavior from CVI 2012, but it is not documented in the function help.  Was this change deliberate?