bad label for colorbar when plotting constant field


I am having a problem with the colorbar when plotting a constant field.

The small script below will generate a plot that is a solid blue image with a
solid blue colorbar. However
the label on the colorbar is garbage. There is no way to read the label to
determine what value the image represents.

Has anyone else had a similar problem? How do I fix it?

I am running matplotlib version 1.0.1 installed from macports -- py26-matplotlib




import matplotlib.pyplot as plt
import numpy as np

C = np.matrix('1 1 1; 1 1 1; 1 1 1')