fix bug with not updating the last line correctly when a group was deleted and recreated (bug 1685312); added a unit test for this

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45557 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/fileconf.cpp

@@ -1730,7 +1730,7 @@ bool wxFileConfigGroup::DeleteSubgroup(wxFileConfigGroup *pGroup)
 
             m_pLastGroup = NULL;
             for ( wxFileConfigLineList *pl = pLine->Prev();
-                  pl && pl != m_pLine && !m_pLastGroup;
+                  pl && !m_pLastGroup;
                   pl = pl->Prev() )
             {
                 // does this line belong to our subgroup?
@@ -1744,6 +1744,9 @@ bool wxFileConfigGroup::DeleteSubgroup(wxFileConfigGroup *pGroup)
                         break;
                     }
                 }
+
+                if ( pl == m_pLine )
+                    break;
             }
         }