/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/ is in python3-matplotlib 1.5.1-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/__init__.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/anchored_artists.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/axes_divider.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/axes_grid.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/axes_rgb.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/axes_size.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/colorbar.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/inset_locator.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/mpl_axes.py
/usr/lib/python3/dist-packages/mpl_toolkits/axes_grid1/parasite_axes.py