Service Worker weird caching

Created by: gabrielmicko

Is this a bug report?

Yes

Did you try recovering your dependencies?

Yes

Which terms did you search for in User Guide?

https://github.com/facebook/create-react-app/issues/2398

Environment

Environment Info:

System: OS: macOS High Sierra 10.13.6 CPU: x64 Intel(R) Core(TM) i5-5257U CPU @ 2.70GHz Binaries: Node: 9.10.0 - /usr/local/bin/node Yarn: 1.10.1 - /usr/local/bin/yarn npm: 5.6.0 - /usr/local/bin/npm Browsers: Chrome: 69.0.3497.100 Firefox: 62.0.3 Safari: 12.0 npmPackages: react: ^16.5.2 => 16.5.2 react-dom: ^16.5.2 => 16.5.2 react-scripts: 2.0.4 => 2.0.4 npmGlobalPackages: create-react-app: 2.0.3

Steps to Reproduce

(Write your steps here:)

Clone https://github.com/gabrielmicko/react-create-app-pwa. It is almost a clean app of react-create-app.
Install dependencies. yarn install. Create a build. yarn run build.
Run serve -s build (if you don't have serve yarn global add serve), or node server.js.
Open localhost:5000. You should see service worker precaching files.
Do some change in the App.js and run yarn run build again.
Refresh the page and check your console. You should see the new files. It will log an "Update happened" message.
Refresh the page to see the updates.
Can't see the changes I made.

Expected Behavior

After refreshing the page at point 7. I should see my changes.

Actual Behavior

I see the old version of my app.

(Write what happened. Please add screenshots!)

Reproducible Demo

https://www.youtube.com/watch?v=Hl5HbZ0TWoY