Release 20.1.1

[pradyunsg]

Commands to make this PR a thing:

git checkout 20.1
git checkout -b release/20.1.1
git cherry-pick -m 1 369565d
git cherry-pick -m 1 612970b
git cherry-pick -m 1 c74128c
git cherry-pick -m 1 5cac4dc
git cherry-pick -m 1 1dbcd12
<renamed a file, make a commit>
nox -s prepare-release -- 20.1.1
git push origin release/20.1.1 -u --no-verify

[pradyunsg]

Merging and making a release!