Backport PR #31616 on branch 1.0.x (REGR: Fixed AssertionError in groupby)#31703

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

meeseeksmachine:auto-backport-of-pr-31616-on-1.0.xmeeseeksmachine/pandas:auto-backport-of-pr-31616-on-1.0.xCopy head branch name to clipboard