Add more twitter metatags.

app/views/layouts/_head.html.haml

@@ -6,11 +6,17 @@
   %meta{name: 'referrer',    content: 'origin-when-cross-origin'}
   -# Open Graph - http://ogp.me/
+  %meta{property: 'og:type',        content: "object"}
   %meta{property: 'og:site_name',   content: "GitLab"}
   %meta{property: 'og:title',       content: page_title}
   %meta{property: 'og:description', content: page_description}
   %meta{property: 'og:image',       content: page_image}
   %meta{property: 'og:url',         content: request.base_url + request.fullpath}
+
+  %meta{property: 'twitter:card',         content: "summary"}
+  %meta{property: 'twitter:title',        content: page_title}
+  %meta{property: 'twitter:description',  content: page_description}
+  %meta{property: 'twitter:image',        content: page_image}
   = page_card_meta_tags
   - page_title "GitLab"