Language switcher block doesn't render any language link as .active when in node edit form...

...if the site's language and the language of the node being edited are different.

I noticed this when I set a css rule to hide the .active language link. All pages of the site were acting as supposed (only one language available for switching), but on node edit forms sometimes I'd see both of the site's available languages. I then saw that the li items were getting their lang-code and "first"/"last" classes, but none of them had the "active" class attached to it.

I guess this one is the opposite of #220559: Language switcher block highlights ALL languages as active ;)

Steps to reproduce:

1. Enable at least two languages for your site (say English and Italian).
2. Place the language switcher block to a region on your theme.
3. Enable translation for a content type (do not allow language neutral).
4. Create a node of that content type.
5. Translate the node to the other language.
6. View then go to the edit form of one of the node translations (say the Italian one).
7. While in the node edit form, switch the site's language to the other language (English in my example).
8. Check the classes of the language links...

This is easier to see if you have first used this css hack in your theme in order to hide the active language link from the language switcher:

ul.language-switcher-locale-url li.active {
  display: none;
}

Instead of only one flag/link in this case, you'll see both. One would expect that the site's current language link would be active (...thus have the .active class, thus be hidden from display).