add condition to check that convolution is not 3D

theano/gpuarray/dnn.py

@@ -565,6 +565,8 @@ class GpuDnnConv(DnnBase):
                                                     SUPPORTED_DNN_CONV_ALGO_RUNTIME):
             raise ValueError("convolution algo %s can't be used for "
                              "3d convolutions", (self.algo,))
+        if img.type.ndim == 5 and self.num_groups != 1:
+            raise ValueError("Grouped convolutions not implemented for 3D convolutions")
 
         if (not isinstance(desc.type, CDataType) or
                 desc.type.ctype != 'cudnnConvolutionDescriptor_t'):