From f38be98c89d38d62b0f5e5cd6359f55922d06949 Mon Sep 17 00:00:00 2001
From: "Dominik Schilling (ocean90)" <ocean90@git.wordpress.org>
Date: Mon, 24 Nov 2014 22:49:13 +0000
Subject: [PATCH] Clear update caches when site language is changed.

The update screen has a re-install button which could show the wrong language locale after the site language was changed. That's because the update data is cached.
Introduce `_wp_clear_update_cache()` as a helper function to clean up the update cache.

props SergeyBiryukov, ocean90.
fixes #30369.

git-svn-id: https://develop.svn.wordpress.org/trunk@30554 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-admin/includes/class-wp-upgrader.php |  8 ++------
 src/wp-includes/update.php                  | 16 +++++++++++++++-
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/wp-admin/includes/class-wp-upgrader.php b/src/wp-admin/includes/class-wp-upgrader.php
index 3a3cd69dc0..cfb2e3ab40 100644
--- a/src/wp-admin/includes/class-wp-upgrader.php
+++ b/src/wp-admin/includes/class-wp-upgrader.php
@@ -1372,9 +1372,7 @@ class Language_Pack_Upgrader extends WP_Upgrader {
 		remove_filter( 'upgrader_source_selection', array( $this, 'check_package' ) );
 
 		if ( $parsed_args['clear_update_cache'] ) {
-			wp_clean_themes_cache( true );
-			wp_clean_plugins_cache( true );
-			delete_site_transient( 'update_core' );
+			_wp_clear_update_cache();
 		}
 
 		return $results;
@@ -2217,9 +2215,7 @@ class WP_Automatic_Updater {
 			}
 
 			// Clear existing caches
-			wp_clean_plugins_cache();
-			wp_clean_themes_cache();
-			delete_site_transient( 'update_core' );
+			_wp_clear_update_cache();
 
 			wp_version_check();  // check for Core updates
 			wp_update_themes();  // Check for Theme updates
diff --git a/src/wp-includes/update.php b/src/wp-includes/update.php
index bb3b100935..9a46823ce4 100644
--- a/src/wp-includes/update.php
+++ b/src/wp-includes/update.php
@@ -648,8 +648,20 @@ function wp_schedule_update_checks() {
 	}
 }
 
-if ( ( ! is_main_site() && ! is_network_admin() ) || ( defined( 'DOING_AJAX' ) && DOING_AJAX ) )
+/**
+ * Clear existing update caches for plugins, themes, and core.
+ *
+ * @since 4.1.0
+ */
+function _wp_clear_update_cache() {
+	wp_clean_plugins_cache();
+	wp_clean_themes_cache();
+	delete_site_transient( 'update_core' );
+}
+
+if ( ( ! is_main_site() && ! is_network_admin() ) || ( defined( 'DOING_AJAX' ) && DOING_AJAX ) ) {
 	return;
+}
 
 add_action( 'admin_init', '_maybe_update_core' );
 add_action( 'wp_version_check', 'wp_version_check' );
@@ -669,6 +681,8 @@ add_action( 'admin_init', '_maybe_update_themes' );
 add_action( 'wp_update_themes', 'wp_update_themes' );
 add_action( 'upgrader_process_complete', 'wp_update_themes', 10, 0 );
 
+add_action( 'update_option_WPLANG', '_wp_clear_update_cache' , 10, 0 );
+
 add_action( 'wp_maybe_auto_update', 'wp_maybe_auto_update' );
 
 add_action('init', 'wp_schedule_update_checks');