First added in [37588] and later modified in [38224], the idea was to ensure that filters/actions added before `advance-cache.php` would not disappear if `advance-cache.php` overloaded the filters/actions with code such as `$wp_filter = array()`. This is an edge case and one that there is no documented case of existing.
This restores the behavior from WordPress 4.5 and before. It is strongly encouraged that developers using `advance-cache.php` to use the Plugins API that is available before the loading of `advance-cache.php` rather than directly interacting with any of the globals.
Props azaozz, jorbin, dd32 for review, pento for review, westi for investigation, ipstenu for research.
See #36819.
git-svn-id: https://develop.svn.wordpress.org/trunk@38251 602fd350-edb4-49c9-b593-d223f7449a82
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