Database: Don’t trigger _doing_it_wrong() for null values in wpdb::prepare().

While `wpdb::prepare()` does not support null values (see #12819) they still appear in the wild like in the WordPress Importer and other plugins.


Built from https://develop.svn.wordpress.org/trunk@41483


git-svn-id: http://core.svn.wordpress.org/trunk@41316 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41470';
+$wp_version = '4.9-alpha-41483';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.