diff -r f507feede89a -r 09a1c134465b web/wp-includes/ms-default-filters.php
--- a/web/wp-includes/ms-default-filters.php	Wed Dec 19 12:35:13 2012 -0800
+++ b/web/wp-includes/ms-default-filters.php	Wed Dec 19 17:46:52 2012 -0800
@@ -45,6 +45,7 @@
 add_filter( 'import_upload_size_limit', 'fix_import_form_size' );
 add_filter( 'upload_mimes', 'check_upload_mimes' );
 add_filter( 'upload_size_limit', 'upload_size_limit_filter' );
+add_action( 'upload_ui_over_quota', 'multisite_over_quota_message' );
 
 // Mail
 add_action( 'phpmailer_init', 'fix_phpmailer_messageid' );
@@ -60,3 +61,6 @@
 // WP_HOME and WP_SITEURL should not have any effect in MS
 remove_filter( 'option_siteurl', '_config_wp_siteurl' );
 remove_filter( 'option_home',    '_config_wp_home'    );
+
+// If the network upgrade hasn't run yet, assume ms-files.php rewriting is used.
+add_filter( 'default_site_option_ms_files_rewriting', '__return_true' );
\ No newline at end of file