Set scheme before downloading relative scheme URLs.

[peterwilsoncc]

Description of the Change

Before calling the WordPress function download_url() in Utils\process_media() check for relative scheme URLs and set a scheme if required.

WordPress isn't a browser so will throw an error if a request is made to download a relative URL. Defaulting to http will ensure the most likelihood of success, if the site redirects to an HTTPS URL then WordPress will follow the redirect.

See #975

How to test the Change

1. Set up Distributor on two WordPress sites
2. In the wp-config.php file for each site, define WP_CONTENT_URL to use a relative scheme URL: define( 'WP_CONTENT_URL', '//' . $_SERVER['HTTP_HOST'] . '/wp-content' );
3. Connect each site as an external connection to the other
4. On site A, publish a post with a featured image.
5. On site B, pull the post from site A using Distributor

On this branch the post should include the featured image, on develop the featured image should be missing.

Changelog Entry

Fixed - Account for relative scheme URLs when processing media.

Credits

Props @peterwilsoncc

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[ravinderk]

@peterwilsoncc I could not reproduce the issue but did not see the side effect of a minor change. For this reason, I am approving the pull request.