[UX] Detect whether mod_rewrite is enabled (in Apache installs) and throw a warning in the clean URLs page.

Here's the deal... - I see that clean URLs are not enabled, - I head over to ?q=admin/config/search/urls to run the test. Test says "no go". - I know that there's a known issue about this (https://www.drupal.org/node/1134934), so I just give it a go nevertheless by removing the ?q= part of the URL. ...404 - I enable AllowOverride All etc. in my apache settings and restart the service. - I try the clean URL admin/config/search/urls and it works!! - Great, but then going back to the ?q=admin/config/search/urls page shows that "Clean URLs cannot be enabled." and running the test throws a "The clean URL test failed." message. - Fine, try the clean URL again admin/config/search/urls ...it works and gives me the option to enable clean URLs. WTF#1 - Perhaps I need to click the "Enable clean URLs" checkbox to make it stick... so I tick, I hit save aaand... WTF#2: the checkbox is unchecked after the page is reloaded?!?

I repeat the tick and save a couple of times... still the checkbox comes as unchecked ...but the clean URLs work?!? ...well only if I manually type them in the address bar. If I visit the website still all menu links (in primary navigation for example) are using the non-clean form.

Something I'm doing wrong or bug?