1. Upload a review like https://chromium-review.googlesource.com/c/500028/
2. Try to add haraken@chromium.org to the reviewers line.

Expected:
haraken@chromium.org should be added to the review.

Actual:
Polygerrit doesn't seem to understand that haraken@chromium.org is a valid user account. It's really weird, because it shows up on the CC line just fine...