Uses home_url() in get_current_url_supercache_dir

[stodorovic]

• Uses home_url instead of site_url in function get_current_url_supercache_dir.
• Variable $wp_cache_home_path has different value for each site (multisite installation) and it isn't possible to store this variable into wp-cache-config.php. Anyway, we could use better/faster way - parse_url (or wp_parse_url if it exists) to extract only url path.

It's related to old issue.

[donnchawp]

I'm not sure if it's safe to change site_url to home_url. On a site where WordPress is installed "in it's own directory" site_url points at that install path, while home_url points at where the site lives, at least from what I've read and I have vague memories of fixing bugs caused by this in the past.
https://wp-mix.com/wordpress-difference-between-home_url-site_url/
https://wordpress.stackexchange.com/questions/20294/whats-the-difference-between-home-url-and-site-url

I don't have such an install at hand to test this on, but I need to test it before this change goes in.

[stodorovic]

I know for difference between home_url and site_url and I've even changed Wordpress URL on a less important site for monitoring. Also, I've locally installed couple websites (with various WP versions for testing purpose) for experimenting. There are two issues related to site_url: different path (if URLs aren't same) and different protocol (if FORCE_SSL_ADMIN is true).

It's safe to change it because get_permalink uses home_url:

$permalink      = home_url( str_replace( $rewritecode, $rewritereplace, $permalink ) );
$permalink      = user_trailingslashit( $permalink, 'single' );

It's similar for other functions (which get_permalink executes): get_post_permalink, get_page_link, get_attachment_link, ...

It's reason why I think that we should use home_url. Also, it requires testing (I agree with you that we need to double check) to we avoid new issues.