Hook wpmu_new_blog callbacks to wp_insert_site / wp_initialize_site

[iandunn]

Jetpack hooks into the wpmu_new_blog action in two places:

https://github.com/Automattic/jetpack/blob/ca7c26b/modules/likes.php#L80

https://github.com/Automattic/jetpack/blob/b578d60/class.jetpack-network.php#L76

WP 5.1 deprecated that hook in favor of wp_insert_site and wp_initialize_site.

Because of that, notices are being triggered when any plugin calls wp_insert_site(), even if that plugin uses the new hooks correctly. The notice is triggered if any active plugin is using the deprecated hooks. Because of that, local development workflows are broken by headers already sent crashes, and production error logs are cluttered with noise, making them less useful.

Steps to reproduce the issue

1. Activate latest JP on WP 5.1
2. Call wp_insert_site() from an mu-plugin, wp shell, etc

What I expected

No notices should be triggered.

What happened instead

A notice was triggered.

Screenshots

[iandunn]

Just noting that this is still happening, so that Stalebot doesn't close the issue.

[kraftbj]

I'm marking this as 7.4. As soon as WP 5.2 has been released, our minimum supported WP version becomes 5.1 so we can switch to this without any version checks for 5.0 for the old hooks.

[kraftbj]

I'm not going to attempt to fix the Likes reference in the Jetpack PR since that is code that only runs on WordPress.com and the callable being passed to the filter does not exist in the JP codebase.

I'd like it to fix it on the WP.com and bring it over in Fusion.

[iandunn]

Thanks!