Clarified summary: the page display title became available when another non-empty translation unit was added.

Ok, this tested in the http://www.mediawiki.org/wiki/Category:MediaWiki_Introduction/ru

Why this page marked as "50% translation"? There's no untranslated content... Maybe should be two translatable string at least?

To keep an eye on: unlrelated gerrit change 52216 might affect this.

(In reply to comment #3)

To keep an eye on: unlrelated Gerrit change #52216 might affect this.

That patch got merged on March 07, 2013, hence wondering what's the status here.

(In reply to comment #4)

(In reply to comment #3)

To keep an eye on: unlrelated Gerrit change #52216 might affect this.

That patch got merged on March 07, 2013, hence wondering what's the status
here.

IIRC I tested when that was deployed and nothing had changed.
On the original example if you remove the translation unit the mark page for translation link doesn't even appear; I created another test case and there's nothing to translate after «The page has been marked up for translation with 0 translation units. The page can now be translated».
https://www.mediawiki.org/w/index.php?title=Special%3ATranslate&taction=translate&group=page-Category%3ALocalisation+extensions&language=it&limit=100&task=untranslated