Caching does not flush/refresh project data properly

There is a serious caching bug I reported earlier in update_advanced where the source seems to be update module. You need update_advanced to reproduce this.

Enable Check for updates of disabled modules and themes in admin/reports/updates/settings and hit Save configuration. After the settings are saved the table on the page is not complete. If you would Save configuration again - you will lose your update_advanced ignore setting for all currently not shown projects.

To prevent the data loss you need to reload admin/reports/updates/settings as often until the list is complete. This also happens if you have just enabled the update_advanced module or if you change the Check for updates of disabled modules and themes setting. :-(((

The source of this issue seems to be the function update_get_available() that will not always return a complete list of all modules.