Fresh matplotlib install broken: installs qt5, but matplotlib rc patched to require qt4

[jorisvandenbossche]

Related to #1065 (but opening a new issue as this is not a Qt problem but how the matplotlib rc is patched AFAIU). Also reported it at matplotlib: matplotlib/matplotlib#7124 (comment)

When you do a fresh conda install matplotlib, this now installs qt/pyqt 5.x instead of 4.x.
But as far as I understand, anaconda patches matplotlib to default to qt4 backend. With the consequence that you get a ImportError: No module named 'PyQt4' error if you do not specify the backend to qt5agg manually.

Possible workarounds for now (either one of the two):

• pin pyqt to 4.11
• set the backend manually before importing pyplot (matplotlib.use('qt5agg'))

[jorisvandenbossche]

The patch is here: https://github.com/ContinuumIO/anaconda-recipes/blob/master/matplotlib/rctmp_pyside.patch

[ccordoba12]

Thanks @jorisvandenbossche, this means that we need to remove or update that patch so that Matplotlib can work with Qt5.