Can you add a test for this the (the example from #8406 is perfect, only need the png).

Perhaps the test of #8344 already checks that? @dstansby please confirm.

Yep, the change here affects the test added in #8344 , so this change would be caught there.

Given the recent extensive discussion regarding s-g, let's try to make this a bit more efficient (especially for PRs coming from core devs). (Obviously I have also authored not-so-clear PRs so it's also applies to myself).

The problem is that I have no idea what the -2/-1 in the diff means. Of course I could rummage through the arrow plotting code but do I really want to do that? I would be much happier approving/merging this if e.g. @dstansby could post two images, say before/after, and explain what the -2/-1 changes. It can be as simple as "using :-2 drops the point at coordinate x, y which makes the arrow wrong (fig 1); that was done to drop a point at coordinate x, y for the polar plot (fig 2)".

This commit was shared with #8344 which was backported to v2.0.x as 46247c7