A very simple fix for some old entries imploded with '\n' instead of
"\n". As for other scripts, this extends LoggedUpdateMaintenance but it
includes a dry run option to be tested, and a subsequent patch (to be
merged after testing) will add it to update.php.
Bug: T208931
Change-Id: I16d629c05c3b9c9055c68dafd261b0a5c0db9c25