Repository: create-react-app
Issue: Service Worker weird caching
Labels: tag: documentation,issue: question > PWA

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### Is this a bug report?
Yes

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### Did you try recovering your dependencies?

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Yes

### Which terms did you search for in User Guide?

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https://github.com/facebook/create-react-app/issues/2398


### Environment

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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

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(Write your steps here:)

1. Clone https://github.com/gabrielmicko/react-create-app-pwa. It is almost a clean app of react-create-app. 
2. Install dependencies. `yarn install`. Create a build. `yarn run build`.
3. Run `serve -s build` (if you don't have serve `yarn global add serve`), or  `node server.js`.
4. Open localhost:5000. You should see service worker precaching files.
5. Do some change in the `App.js` and run `yarn run build` again.
6. Refresh the page and check your console. You should see the new files. It will log an "Update happened" message.
7. Refresh the page to see the updates.
8. Can't see the changes I  made. 


### Expected Behavior

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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

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https://www.youtube.com/watch?v=Hl5HbZ0TWoY

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