small fix for multistep ensemble training

Author: azrael417

makani/models/stepper.py

@@ -153,11 +153,11 @@ def _forward_eval(self, inp, update_state=True, replace_state=True):
 
         return y
 
-    def forward(self, inp, replace_state=True):
+    def forward(self, inp, update_state=True, replace_state=True):
         # decide which routine to call
         if self.training:
             y = self._forward_train(inp, update_state=True, replace_state=replace_state)
         else:
-            y = self._forward_eval(inp, update_state=True, replace_state=replace_state)
+            y = self._forward_eval(inp, update_state=update_state, replace_state=replace_state)
 
         return y