The recently merged PR #3182 removed 2 lines in each of the examples tricontour_demo.py, tripcolor_demo.py and triplot_demo.py. These lines needed to be altered, not removed. Some of the plots produced are clearly wrong, e.g.

General rules for developers:

1. If you change an example script, run it before and after your changes to see if the output is the same.
2. If someone submits a PR that touches 60 files just prior to a release, either park it until after the release or be very sure it doesn't break anything.