Bug 729378 - delete user subtree container in AD + modify password in DS == DS crash
    
    https://bugzilla.redhat.com/show_bug.cgi?id=729378
    Resolves: bug 729378
    Bug Description: delete user subtree container in AD + modify password in DS == DS crash
    Reviewed by: nkinder, nhosoi (Thanks!)
    Branch: master
    Fix Description: Check for NULL DN in send_password_modify - return error
    if the DN is NULL.
    Platforms tested: RHEL6 x86_64, Windows 2008 64-bit
    Flag Day: no
    Doc impact: no