HTTPS Everywhere upgrade-insecure-header injection appears to be broken on 8.0a9 / 8.0a10

Replying to cypherpunks:

I compared the behavior between 8.0a8 and 8.0a9:

  • Open 8.0a8, and check the "Block all unencrypted requests" in the HTTPS-E popup.

  • Go to a mixedcontent website (go to the github repository efforg/https-everywhere then search for mixedcontent and find recent edited one, here's an example of such a site

  • So open that site up while your browser console is opened, you can see that HTTPS-E injects an upgrade-insecure-requests header and everything is going through HTTPS now including scripts and css etc.

  • Open 8.0a9, and check the "Block all unencrypted requests" in the HTTPS-E popup.

  • Go to the previously mentioned site.

  • There doesn't appear to be any injection of upgrade-insecure-requests header, css broken etc as a result.

This doesn't affect Firefox Nightly 63a1.