added missing variable initialisation for stop, removed outdated comment, removed whitespaces

theano/sandbox/cuda/basic_ops.py

@@ -2987,7 +2987,6 @@ class GpuJoin(tensor.Join, GpuOp):
                 shape_%(cdna)s[i] = CudaNdarray_HOST_DIMS(%(cdna)s)[i];
                 if((i!=axis) && (shape_%(cdna)s[i]!=shape_out[i]))
                 {
-                    // compilation error when `fail`-string is added
                     %(fail)s;
                 }
             }
@@ -3012,9 +3011,11 @@ class GpuJoin(tensor.Join, GpuOp):
         full_slice = PySlice_New(NULL, NULL, NULL);
         PyObject *out_sub;
         PyObject *start, *stop, *step;
+        start = NULL;
+        stop = NULL;
         step = NULL;
         sum = 0;
-        start = NULL;
+
         """ % locals()
         # start copying the data into the new out tensors
         for i, cdna in enumerate(inputs[1:]):