Core Updates: Fix a case where options (db_version specifically) can end up with stale values in the cache after a update is performed. Fixes #26173 for trunk.

git-svn-id: https://develop.svn.wordpress.org/trunk@26448 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/update-core.php

@@ -892,6 +892,9 @@ function update_core($from, $to) {
 	$db_upgrade_url = admin_url('upgrade.php?step=upgrade_db');
 	wp_remote_post($db_upgrade_url, array('timeout' => 60));
 
+	// Clear the cache to prevent an update_option() from saving a stale db_version to the cache
+	wp_cache_flush();
+
 	// Remove working directory
 	$wp_filesystem->delete($from, true);