There is no formal 4.3.1 version released until now. The comment for 4.3.1 was just telling that it will be placed on 4.3.1, but doesn't mean it was released.
For that issue, the fix for 4.3.0 is here: https://github.com/ezsystems/ezpublish/commit/d5587abf764f764c78def5817cc302c649b15ceb . You can use the patch as a workaround.
