Bug report

Bug summary

1. sudo apt-get install fonts-wqy-microhei
2. can not refresh or get new font in running interpreter/notebook
   

But it can read new font in new notebook

Matplotlib version

• Operating system: ubuntu
• Matplotlib version: 3.1.2
• Matplotlib backend (print(matplotlib.get_backend())): module://ipykernel.pylab.backend_inline
• Python version: 3.7
• Jupyter version (if applicable):

jupyter core     : 4.6.1
jupyter-notebook : 6.0.2
qtconsole        : not installed
ipython          : 7.11.1
ipykernel        : 5.1.3
jupyter client   : 5.3.4
jupyter lab      : not installed
nbconvert        : 5.6.1
ipywidgets       : not installed
nbformat         : 5.0.3
traitlets        : 4.3.3