Backport PR #17499: Fix scatter singlecolor#17501

tacaswell merged 1 commit intomatplotlib:v3.2.xmatplotlib/matplotlib:v3.2.xfrom

tacaswell:auto-backport-of-pr-17499-on-v3.2.xtacaswell/matplotlib:auto-backport-of-pr-17499-on-v3.2.xCopy head branch name to clipboard