Regression: imshow on geo axes produces an empty plot in matplotlib 2.0.0 #7903

Bug summary

In Matplotlib 1.5.3, it was possible to use imshow on geo axes (e.g. the mollweide projection defined in matplotlib.projections.geo. In Matplotlib 2.0.0, this produces a blank plot.

Code for reproduction

Here is an example that worked in 1.5.3.

from matplotlib import pyplot as plt
import numpy as np

lon = np.linspace(-np.pi, np.pi)
lat = np.linspace(-np.pi/2, np.pi/2)
lon, lat = np.meshgrid(lon, lat)

ax = plt.axes(projection='mollweide')
ax.grid()
ax.imshow(lon, extent=[-np.pi, np.pi, -np.pi/2, np.pi/2], aspect=ax.get_aspect())
plt.savefig('test.png')

Actual outcome

This is the output on Matplotlib 2.0.0: blank axes.

Expected outcome

This was the output in Matplotlib 1.5.3.

Matplotlib version

Installed from MacPorts on OS X 10.11.6 "El Capitan". Port versions:

• py27-matplotlib @1.5.3_0+cairo
• py27-matplotlib @2.0.0_0+cairo