When viewed from above, the default grids are not square, but are distorted into diamonds/parallelograms depending on the vertical rotation angle:

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

fig = plt.figure()
ax = fig.gca(projection='3d')
ax.view_init(90,45)  # or by manual rotation
plt.show()

The projection should not include non-uniform scale (or skew) components by default. Furthermore, it's not at all obvious how to fix this as a user.

Couldn't find another issue that directly reports this, so put it here.

Related are #1104 and #1077