Added test case for warp() when cval out of clipping range

skimage/transform/_geometric.py

@@ -786,6 +786,7 @@ def warp(image, inverse_map=None, map_args={}, output_shape=None, order=1,
     # The spline filters sometimes return results outside [0, 1],
     # so clip to ensure valid data
     clipped = np.clip(mapped, 0, 1)
+
     if mode == 'constant' and not (0 <= cval <= 1):
         clipped[mapped == cval] = cval