Issue with HTTPS redirect in WordPress

Within certain conditions, a WordPress site is rendered completely inoperable by CiviCRM. This is most likely due to a conflict with the HTTPS redirect, other components of the WordPress integration, other WordPress plugins and/or the Apache mpm-itk module that leads to a race condition.

Conditions to reproduce:

• have a WordPress site with a menu item that links to a donation page
• the links is with http, but the redirect to https is configured in CiviCRM
• the donation page includes a shortcode for a CiviCRM contribution page
• clear all cookies related to the site
• go to the home page over http (1)
• click on the donation page link (2)

At this point in time, the symptoms are:

• the screen does not change and the tab icons keeps spinning
• there are 2 Apache processes on the servers, both are in stuck in sending state, both are on the /donate URL, one if from the remote IP, the other one is from 127.0.0.1
• a cookie file was created after (1) and was non-zero in length, the same cookie file is now of length 0
• clicking on any other link on the screen, stopping and reloading the page or any other page on the site leads to the same infinitely spinning page that does not load
• clearing all cookies for the site in your browser, and then everything works again

The only way to fix this is either to have the link to the donate page over https rather than http. Once you do this, all works seamlessly.