Change CTC lifter optimization to return apply node's outputs

theano/gpuarray/opt.py

@@ -2299,10 +2299,7 @@ def local_gpu_magma_svd(op, context_name, inputs, outputs):
 @register_opt2([ConnectionistTemporalClassification], 'ctc', 'fast_compile')
 def local_gpu_ctc(op, context_name, inputs, outputs):
     op = GpuConnectionistTemporalClassification(compute_grad=op.compute_grad)
-    if op.compute_grad:
-        # Circumvent assert error on condition len(outputs) == len(node.outputs)
-        op.default_output = None
-    return op
+    return op.make_node(*inputs).outputs
 
 
 # Do not register in fast_run or fast_compile.