Probably since PLANET-6895

Site title (ie "Greenpeace International") appears twice in the site <title> tag.

The context variable `og_title` is always filled by the code even if not completed in a post - and when it's empty, the site name is appended to it (cf Post::get_og_title); using it the same way `wp_title` is used leads to a double site name. 

Tasks

• check all the ways the title is generated
• append site name in equivalent ways for wp_title and og_title