Version: 52.0.2719.0 (Developer Build) (64-bit)
OS: Linux (but likely platform-independent)

What steps will reproduce the problem?
(1) Go to https://w3c.github.io/webappsec/demos/credential-management/.
(2) Click sign-in, choose one of the buttons with federations.
(3) Click Never in the bubble offering to save the federated credential.
(4) Repeat steps 1 and 2.
(5) Either repeat step 3 or type in some credentials in the form and hit Submit.

What is the expected output?
No offer to save anything, because of the blacklisting.

What do you see instead?
The blacklisting is ignored and both federated and username/password credentials are offered for saving.