wp-admin/includes/upgrade.php:2185Executes changes made in WordPress 5.1.0.
function upgrade_510() { delete_site_option( 'upgrade_500_was_gutenberg_active' );}Introduced in 5.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/upgrade.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.