Set the bucket to B. Integration has no CDN and no A/B cookies, this just sets the header that would be sent with the request.
Visit the A/B page in on Production.
If this happens to place you in the B bucket, everything is consistent, and the extension works as expected. But if you are placed in the A bucket, your A/B cookie will say 'A' but the extension will show 'B'.
This fixes issues like this:
https://trello.com/c/jra1OClm/320-make-it-easy-to-test-experiments-in-non-prod-environments
Marked as DO NOT MERGE because it depends on on #58. If that gets merged, I'll rebase and update the merge base for this PR.