Firefox – way to selectively clear or delete cache specific to one website or domain in Firefox

1. Select the Firefox Menu button (three horizontal lines on the right).
2. Select Library.
3. Select History.
4. Scroll to the bottom and select Show All History.
5. Search for the site using the Search History field in the upper-right corner.
6. Within the results, right-click the appropriate page and select Forget About This Site.

Note: This will clear saved passwords for the site as well.

Locate the site you are redirected from in the History sidebar. Right-click it and select "Forget about this site".

No addons required!

P.S. I'm pretty sure this didn't work in the past, but nowadays following the redirect and then clearing the cache for past hour will actually remove the cached redirect.

P.S. The current best solution is to use "Web Developer Tools" (Ctrl+Alt+I), click "Network" and click "Disable cache". Load the original URL. Enable the cache again. The page is refreshed in the cache and the original URL is accessible also from other tabs now.