Ticket #31203: 31203.patch

src/wp-includes/class-wp-customize-control.php

@@ -1243 +1243 @@
 class WP_Customize_New_Theme_Control extends WP_Customize_Control {
 
         /**
-         * Render the new control.
+         * Render the control content.
          *
          * @since 4.2.0
          */
-        public function render() {
-                if ( is_multisite() || ! current_user_can( 'install_themes') ) {
-                        return;
-                }
+        public function render_content() {
                 ?>
                 <div class="theme add-new-theme">
                         <a href="<?php echo admin_url( 'theme-install.php' ); ?>" target="_top">

src/wp-includes/class-wp-customize-manager.php

@@ -1171 +1171 @@
                         ) ) );
                 }
 
-                $this->add_control( new WP_Customize_New_Theme_Control( $this, 'add_theme', array(
-                        'section' => 'themes',
-                        'settings' => 'active_theme',
-                ) ) );
+                if ( ! is_multisite() && current_user_can( 'install_themes' ) ) {
+                        $this->add_control( new WP_Customize_New_Theme_Control( $this, 'add_theme', array(
+                                'section' => 'themes',
+                                'settings' => 'active_theme',
+                        ) ) );
+                }
 
                 /* Site Title & Tagline */