Core updates: Explicitly call wp_cache_delete() after a DB upgrade, as not all cache backends allow the entire backend to be flushed.

props dd32.
fixes #26173.

Built from https://develop.svn.wordpress.org/trunk@26734


git-svn-id: http://core.svn.wordpress.org/trunk@26623 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/update-core.php

@@ -894,6 +894,8 @@ function update_core($from, $to) {
 
 	// Clear the cache to prevent an update_option() from saving a stale db_version to the cache
 	wp_cache_flush();
+	// (Not all cache backends listen to 'flush')
+	wp_cache_delete( 'alloptions', 'options' );
 
 	// Remove working directory
 	$wp_filesystem->delete($from, true);