I just watched a developer get caught up on this issue.

What steps will reproduce the problem?
(1)Visit a site with service worker support: https://airhorner.com/
(2)Open DevTools and go to Application Tab
(3)Refresh the page and notice it briefly shows a new service worker marked and 'installing'

What is the expected output?
Would be ideal if DevTools highlighted that it was checking for an update to the current service worker rather than installing a new service worker.

What do you see instead?
The UI suggested that it was actually installing a new service worker.