robust the prefit

quickstats/components/extended_minimizer.py

@@ -625,7 +625,7 @@ class ExtendedMinimizer(AbstractObject):
                 # prefit minimization
                 self.minimizer.setStrategy(0)
                 self.minimizer.setEps(self.config['eps']*10)
-                status = self.single_minimize(self.config['minimizer_type'], self.config['minimizer_algo'])
+                self.robust_minimize(cascade=cascade)
                 self.minimizer.setStrategy(self.config['strategy'])
                 self.minimizer.setEps(self.config['eps'])