With the CIAO 4.11 code base (so close to master) and matplotlib version 2.2.3, I see the following behavior, where some, but not all calls to plot data/model/residuals/ ... inconsistent warning for ...

matplotlib will crash when a log scale is used for the radial axis of a polar plot, unless very specific commands are used to create the plot. The following code will cause a crash: import numpy as np ...