When using relative URL instalation , wiki links are broken

gitlab version: gitlab-ce 8.7.0-ce.0

installation: using relative url

When I fixed manually !3924 (merged) I'm facing new issue.

Sorry for being annonymous, but can't paste here the installation URL.

Installatation URL: https://relative.example.com/source/

Project group: project_group

Project: project

wiki home page code

[link to another page](another-page)

This should point to

https://relative.example.com/source/project_group/project/wikis/another-page

but points to

https://relative.example.com/project_group/project/wikis/another-page

the relative part source is missing.