Gouraud shading with tripcolor renders incorrectly as SVG in Jupyter notebook

Bug report

Bug summary

When the matplotlib backend is set to 'SVG' in a Jupyter Notebook, it seems that matplotlib does not render 'gouraud' shading correctly.

Code for reproduction

I've uploaded a minimal example of my problem here:
https://nbviewer.jupyter.org/github/CorbinFoucart/FEMexperiment/blob/master/app/mpl_bug.ipynb

Actual outcome

Note the 'gouraud' shading with SVG in the notebook. If I save the output to file and view the output, it is similarly not shaded, which indicates to me that this is not a Jupyter issue, nor a browser issue.

Matplotlib version

• Operating system: OSX El Capitan 10.11.6
• Matplotlib version: 2.2.2
• Matplotlib backend (print(matplotlib.get_backend())): module://ipykernel.pylab.backend_inline
• Python version: 3.6.4
• Jupyter version:

ipykernel==4.8.2
jupyter==1.0.0
jupyter-client==5.2.3
jupyter-console==5.2.0
jupyter-core==4.4.0

I installed matplotlib in a virtual environment with pip.

首先，使用 SVG 後端執行連結的最小重現 mpl_bug.ipynb，並檢查 notebook 輸出和儲存的 SVG。追蹤使用 gouraud 陰影的 tripcolor 之 SVG 渲染路徑。當陰影在 notebook 和儲存的輸出中都能正確顯示時，即表示完成。