PVS-Studio warning V519 for FireFlies

CDXUTControl::CDXUTControl( CDXUTDialog* pDialog )
{
  ...
  m_pDialog = pDialog;
  ...
  m_pDialog = NULL;
  ...
}

This suspicious code was found in FireFlies project by PVS-Studio static code analyzer.
Warning message is:
V519 The 'm_pDialog' variable is assigned values twice successively. Perhaps this is a mistake. Check lines: 3470, 3481. DXUTOpt dxutgui.cpp 3481

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/