Set "Matplotlib" backend during distribution tests.
@@ -394,7 +394,7 @@ def virtualise(ctx, tests=True):
ctx.run('python -c "import imageio;'
'imageio.plugins.freeimage.download()"')
if tests:
- ctx.run('poetry run nosetests')
+ ctx.run('poetry run nosetests', env={'MPLBACKEND': 'AGG'})
@task
