NOTE: All tests must be performed under an SSL connection (the "https://" URLs) with a valid SSL certificate (green lock)
# delete `/system/config.php` file
# go to Homepage (e.g. `/`)
# confirm, that the "Go to installation script" link, that is shown, has the same protocol as the visited page
# apply D403 patch
# perform In-Portal installation with all the modules using SSL connection (`https://` protocol)
# confirm, that the SSL connection lock is not broken across the whole installation process