[Matplotlib-users] why does transform=None cause a patch not to be shown?

[C M <cmp...@gm...>]

For the following code, if I remove the transform=None a green patch is
shown.  If it is in, it is not shown.  I would think that transform=None
should have no effect.  Why is this?

Thanks,
Che


import matplotlib.pyplot as plt
import matplotlib.patches as patches
from matplotlib.path import Path

fig = plt.figure()
ax = fig.add_subplot(111)

start = 0.2
stop = .6

verts = [
    (start, .2), # left, bottom
    (start, .4), # left, top
    (stop, .4), # right, top
    (stop, .2), # right, bottom
    (0., 0.), # ignored
    ]
codes = [Path.MOVETO,
         Path.LINETO,
         Path.LINETO,
         Path.LINETO,
         Path.CLOSEPOLY,
         ]

path = Path(verts, codes)

patch = patches.PathPatch(path, facecolor='g',
                          lw=1, edgecolor='grey',transform=None )

ax.add_patch(patch)

plt.show()