Seeing null wiki markup link when linking to an old version of a page

This was reported by a customer when he was trying to link an old version of a page.

The wiki markup link will be shown as [null:page title].

It should either be not there at all if this is not yet supported. Alternatively, improve the functionality as to allow using wiki markup to link to an old page version.

See screenshot: broken.jpg.

Steps to replicate:

1.) create a page
2.) alter that page
3.) go to history
4.) select a previous version
5.) click tools > link to this page
6.) it will then show a null in the wiki markup

If the new feature is implemented, this doc needs to be updated as well.