Backport PR #31136 on branch 1.0.x (COMPAT: Return NotImplemented for subclassing)#31405

TomAugspurger merged 1 commit intopandas-dev:1.0.xpandas-dev/pandas:1.0.xfrom

meeseeksmachine:auto-backport-of-pr-31136-on-1.0.xmeeseeksmachine/pandas:auto-backport-of-pr-31136-on-1.0.xCopy head branch name to clipboard