diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/cache-compat.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/cache-compat.php	Tue Dec 15 13:49:49 2020 +0100
@@ -0,0 +1,37 @@
+<?php
+/**
+ * Object Cache API functions missing from 3rd party object caches.
+ *
+ * @link https://codex.wordpress.org/Class_Reference/WP_Object_Cache
+ *
+ * @package WordPress
+ * @subpackage Cache
+ */
+
+if ( ! function_exists( 'wp_cache_get_multiple' ) ) :
+	/**
+	 * Retrieves multiple values from the cache in one call.
+	 *
+	 * Compat function to mimic wp_cache_get_multiple().
+	 *
+	 * @ignore
+	 * @since 5.5.0
+	 *
+	 * @see wp_cache_get_multiple()
+	 *
+	 * @param array  $keys  Array of keys under which the cache contents are stored.
+	 * @param string $group Optional. Where the cache contents are grouped. Default empty.
+	 * @param bool   $force Optional. Whether to force an update of the local cache
+	 *                      from the persistent cache. Default false.
+	 * @return array Array of values organized into groups.
+	 */
+	function wp_cache_get_multiple( $keys, $group = '', $force = false ) {
+		$values = array();
+
+		foreach ( $keys as $key ) {
+			$values[ $key ] = wp_cache_get( $key, $group, $force );
+		}
+
+		return $values;
+	}
+endif;