Bug report

Bug summary

If I make a contour plot, and add some clipping, then when I zoom, then the wrong parts of the plot get clipped.

Code for reproduction

# Paste your code here
import matplotlib
from matplotlib import pyplot
import numpy as np

n=100
tmp = np.random.randn(n,n)
for k in range(2):
    tmp = np.cumsum(np.cumsum(tmp,0+k),1-k)

t=np.linspace(-1,1,n)*np.pi
xc=np.cos(t)
yc=np.sin(t)

ax=pyplot.gca()
path = matplotlib.path.Path(np.transpose(np.array([xc, yc])))
patch = matplotlib.patches.PathPatch(path, facecolor='none')
ax.add_patch(patch)

x=np.linspace(-1,1,n)
y=np.linspace(-1,1,n)
cs=pyplot.contour(x,y,tmp,101)

for col in cs.collections:
    col.set_clip_path(patch)

ax.plot(xc,yc,'r')

pyplot.show()

Actual outcome

and then I zoom, via the zoom tool on the left half of the figure

Expected outcome

I expect to be able to see all of the contours on the left side that I saw before.

This did work for a previous version of matplotlib. Just tested (and works) with matplotlib 2.2.2 on QtAgg backend on python 2.7.15, as well as matplotlib 3.1.1 on QtAgg backend on python 3.6.7:

zoomed in:

Matplotlib version1

• Operating system: Mac OSX - 10.15.7
• Matplotlib version (import matplotlib; print(matplotlib.__version__)): 3.3.4
• Matplotlib backend (print(matplotlib.get_backend())): TkAgg
• Python version: Python 3.7.10
• Installed via macports

Matplotlib version2

• Operating system: Linux **** 2.6.32-754.35.1.el6.x86_64 #1 SMP Sat Nov 7 12:42:14 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
• Matplotlib version (import matplotlib; print(matplotlib.__version__)): 3.3.2, 3.3.3
• Matplotlib backend (print(matplotlib.get_backend())): Qt5Agg
• Python version: Python 3.7.10, 3.7.8
• Installed via conda from conda-forge channel