Other versions linking between branches on methods pages seems to be broken

Migrated issue

Reported by: jhodgdon

Apparently, class methods in two different branches don't link to each other. For instance:
http://api.drupal.org/api/drupal/core--modules--entity--entity.query.inc/function/EntityFieldQuery%3A%3Aexecute/8
http://api.drupal.org/api/drupal/includes--entity.inc/function/EntityFieldQuery%3A%3Aexecute/7

They are both EntityFieldQuery::execute() methods, but at the top of the page for the D7 one, you don't see a link to the D8 one, and vice versa.

The classes link to each other, but not the methods.

Here's another example: ArchiverTar::add():
http://api.drupal.org/api/drupal/core--modules--system--system.archiver.inc/function/ArchiverTar%3A%3Aadd/8
http://api.drupal.org/api/drupal/modules--system--system.archiver.inc/function/ArchiverTar%3A%3Aadd/7

The classes are linked:
http://api.drupal.org/api/drupal/core--modules--system--system.archiver.inc/class/ArchiverTar/8
http://api.drupal.org/api/drupal/modules--system--system.archiver.inc/class/ArchiverTar/7

So in my sample of two, it seems to be broken for both.

I also just checked my test site (running the latest code), and the links are missing for ArchiverTar::add() there too.