Wiki home page fails to render when logged out
### Summary
When logged in, the wiki home page renders as the project home page. But when logged out, an issue list is shown.
### Steps to reproduce
* Log in
* Create a new project
* Disable the repository
* Create a wiki home page
* Open the project front page [A]
* Log out
* Open/refresh the project front page [B]
### Example Project
https://gitlab.com/david.libremone/wiki-milestone-example
(You can simply visit this URL while logged into gitlab.com and again when logged out to see the difference.)
### What is the current *bug* behavior?
* [A] When logged in, wiki home page renders as project front page (correct)
* [B] When logged out, issue list renders as project front page (incorrect)
### What is the expected *correct* behavior?
* [A] When logged in, wiki home page renders as project front page
* [B] When logged out, wiki home page renders as project front page
### Relevant logs and/or screenshots
N/A
### Output of checks
This bug happens on GitLab.com
(It also happens on an installation of GitLab with EE functionality disabled. In other words, functionally GitLab CE.)
### Possible fixes
N/A
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