Index: src/wp-includes/class-wp-customize-nav-menus.php
===================================================================
--- src/wp-includes/class-wp-customize-nav-menus.php	(revision 34267)
+++ src/wp-includes/class-wp-customize-nav-menus.php	(working copy)
@@ -934,7 +934,7 @@
 			'renderQueryVar'        => self::RENDER_QUERY_VAR,
 			'renderNonceValue'      => wp_create_nonce( self::RENDER_AJAX_ACTION ),
 			'renderNoncePostKey'    => self::RENDER_NONCE_POST_KEY,
-			'requestUri'            => '/',
+			'requestUri'            => home_url(),
 			'theme'                 => array(
 				'stylesheet' => $this->manager->get_stylesheet(),
 				'active'     => $this->manager->is_theme_active(),
@@ -944,7 +944,7 @@
 		);
 
 		if ( ! empty( $_SERVER['REQUEST_URI'] ) ) {
-			$exports['requestUri'] = esc_url_raw( home_url( wp_unslash( $_SERVER['REQUEST_URI'] ) ) );
+			$exports['requestUri'] = esc_url_raw( wp_unslash( $_SERVER['REQUEST_URI'] ) );
 		}
 
 		printf( '<script>var _wpCustomizePreviewNavMenusExports = %s;</script>', wp_json_encode( $exports ) );