fixes eval mode in InstanceNorm (pytorch#1604)

fixes pytorch#1541

Author: DmitryUlyanov

torch/nn/modules/instancenorm.py

@@ -26,7 +26,7 @@ def forward(self, input):
 
         out = F.batch_norm(
             input_reshaped, running_mean, running_var, weight, bias,
-            self.training, self.momentum, self.eps)
+            True, self.momentum, self.eps)
 
         # Reshape back
         self.running_mean.copy_(running_mean.view(b, c).mean(0))