Bug report

Bug summary

~/.matplotlib/matplotlibrc is not being read

Code for reproduction
I have a matplotlibrc file with a single entry:

backend: qt5agg

This worked fine until I recently upgraded to both Python 3.6 and matplotlib 2.0. I had been using matplotlib 2.0 rc1 without a problem. But now matplotlib is not reading this startup file and I'm forced to specify qt5agg in my Python code.

Actual outcome

import matplotlib
matplotlib.matplotlib_fname()
'/home/dan/scipydev/venv/lib/python3.6/site-packages/matplotlib/mpl-data/matplotlibrc

Expected outcome

import matplotlib
matplotlib.matplotlib_fname()
'/home/dan/.matplotlib/matplotlibrc

Matplotlib version
matplotlib 2.0
virtual environment
Python 3.6
Ubuntu 16.04.1 LTS.

installed with pip into the virtual environment