Ticket #48146 - async simple paged results issue
    
    Description: commit 5060d11f5039efa8534a8b65392ac6e10cbd2168 introduced
    a regression.  Handling backend "be" should be done after checking OID
    MTN_CONTROL_USE_ONE_BACKEND_EXT_OID in the request control.
    
    https://fedorahosted.org/389/ticket/48146
    
    Reviewed by mreynolds@redhat.com (Thank you, Mark!!)
    
    (cherry picked from commit bd2c0d0b6a499d7f91a36e8a9feb83e4fbd3dac5)