Disabling HTTPS redirection for migration

I migrated a WordPress 4.3 site from Register.com to MediaTemple today and found that the forced SSL is causing issues for the staging URL.

In order to try again I have (on the live Register.com site)

• Disabled plugin ‘WordPress HTTPS’
• Removed define( 'FORCE_SSL_ADMIN', true ); from wp-config
• In General Settings replaced https w http for URLs and saved
• Saved permalinks just in case
• verified that .htaccess is not redirecting to https via mod_rewrite

Tried logging out and accessing site and still get redirected from http to https.

Assuming my predecessor has not done anything truly crazy what am I missing there? Where should I look?

In the active theme I found the redirection in header.php

Once commented out the issue was resolved.

if($_SERVER["HTTPS"] != "on")
{
    header("Location: https://" . $_SERVER["HTTP_HOST"] . $_SERVER["REQUEST_URI"]);
   exit();
}