Added _user_requested_quit to debug mode for mrdna script

bin/mrdna

@@ -117,6 +117,7 @@ if __name__ == '__main__':
         while True:
             try:
                 # pdb._runscript(mainpyfile)
+                self._user_requested_quit = False
                 pdb.runcall(main)
                 if pdb._user_requested_quit:
                     break