Fix a crash

theano/sandbox/cuda/dnn.py

@@ -674,7 +674,7 @@ def dnn_conv(img, kerns, border_mode='valid', subsample=(1, 1),
         # Special case: We can be faster by using GpuDnnConvGradI to compute
         # the full convolution as the backward pass of a valid convolution.
         # We just need to set up a suitable 'fake' valid convolution.
-        img = cp_on_negative_strides(img)
+        img = gpu_contiguous(img)  # cudnn v1 and v2 rc3 need contiguous data
         kerns = gpu_contiguous(kerns.dimshuffle(1, 0, 2, 3))
         conv_mode = 'cross' if conv_mode == 'conv' else 'conv'
         shape2 = shape_i(img, 2, fgraph) + shape_i(kerns, 2, fgraph) - 1