dselect: Fix variable usage after delete when using --debug

debian/changelog

@@ -12,6 +12,7 @@ dpkg (1.15.8) UNRELEASED; urgency=low
     - Remove embedded gettext files from the repository, now properly
       installed by autopoint for all po/ directories.
     - Add versioned Build-Depends.
+  * Fix variable usage after delete in dselect.
 
   [ Updated programs translations ]
   * Russian (Yuri Kozlov). Closes: #579149

dselect/pkgsublist.cc

@@ -184,8 +184,8 @@ void repeatedlydisplay(packagelist *sub,
     }
     if (unredisplay) unredisplay->startdisplay();
   }
-  delete sub;
   if (debug) fprintf(debug,"repeatedlydisplay(packagelist[%p]) done\n",sub);
+  delete sub;
 }
 
 int packagelist::deletelessimp_anyleft(showpriority than) {