remove assert in get_conv_grad*

theano/tensor/nnet/abstract_conv.py

@@ -184,7 +184,6 @@ def get_conv_gradweights_shape(image_shape, top_shape,
     if filter_dilation is None:
         filter_dilation = np.ones(len(subsample), dtype='int')
     if num_groups > 1:
-        assert len(subsample) == 2
         nchan = nchan // num_groups
 
     if isinstance(border_mode, tuple):
@@ -295,7 +294,6 @@ def get_conv_gradinputs_shape(kernel_shape, top_shape,
     if filter_dilation is None:
         filter_dilation = np.ones(len(subsample), dtype='int')
     if num_groups > 1:
-        assert len(subsample) == 2
         nkern = nkern * num_groups
 
     if isinstance(border_mode, tuple):