yorkiebar on "4.5 update broke my sites with 301 redirects"

Hi all,

I have a few sites all running the same content with a few country specific differences, each under different domain names. This has worked perfectly for years. Each site has it's own entry under Apache, each having it's own wp-config.php with these two lines:
define('WP_HOME','http://www.optilead.com/');
define('WP_SITEURL','http://www.optilead.com/');
to tell each instance what it is.

The latest WordPress update just broke it, but only for the homepage, which now redirects to the main site (the URL entered on the General Settings page in WP-Admin).

So:
http://www.optilead.co.uk/ (this is the main site and works fine)
http://www.optilead.com/ (this now redirects to the above)

Anyone have any ideas as to how to stop it issuing the 301 redirects and just serve the content like it used to before the update?

Thanks.