#215992 by dww: provide information for upgrades from Drupal 5 with update status module

CHANGELOG.txt

@@ -90,6 +90,8 @@ Drupal 6.0, xxxx-xx-xx (development version)
 - Added support for triggering configurable actions.
 - Added the Update status module to automatically check for available updates
   and warn sites if they are missing security updates or newer versions.
+  Sites deploying from CVS should use http://drupal.org/project/cvs_deploy.
+  Advanced settings provided by http://drupal.org/project/update_advanced.
 - Upgraded the core JavaScript library to jQuery version 1.2.
 - Added a new Schema API, which provides built-in support for core and
   contributed modules to work with databases other than MySQL.

modules/update/update.install

@@ -7,6 +7,8 @@
 function update_install() {
   // Create cache table.
   drupal_install_schema('update');
+  // Remove stale variables from update_status 5.x contrib, if any.
+  _update_remove_update_status_variables();
 }
 
 /**
@@ -38,3 +40,25 @@ function update_schema() {
   return $schema;
 }
 
+/**
+ * Private helper to clear out stale variables from update_status 5.x contrib. 
+ *
+ * @see update_install()
+ * @see update_update_6000()
+ */
+function _update_remove_update_status_variables() {
+  variable_del('update_status_settings');
+  variable_del('update_status_notify_emails');
+  variable_del('update_status_check_frequency');
+  variable_del('update_status_notification_threshold');
+  variable_del('update_status_last');
+  variable_del('update_status_fetch_url');
+}
+
+/**
+ * Clear out stale variables from update_status.
+ */
+function update_update_6000() {
+  _update_remove_update_status_variables();
+  return array();
+}