Wiki search doesn't work with project repository disabled
### Summary
The search finds wiki pages (there `Wiki (8)`) but it still displays:
`We couldn't find any wiki results matching ...`
If I change my search term it finds other results `Wiki (52)` but it still displays:
`We couldn't find any wiki results matching ...`
### Steps to reproduce
The problem only happens if the Repository features are disabled in the project settings.
Unfortunately I can only reproduce it locally
Following some more information:
I always get back the following result for:
search/count?project_id=121&repository_ref=master&scope=issues&search=test&snippets=
```
{"count":"0"}
```
The browser shows me that it gets a 304, json cached
### What is the current *bug* behavior?
Search results are not displayed, only the count.
### What is the expected *correct* behavior?
Search results are displayed, and match the count.
### Relevant logs and/or screenshots

### Output of checks
#### Results of GitLab environment info
<details>
<summary>Expand for output related to GitLab environment info</summary>
<pre>
(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)
(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)
</pre>
</details>
#### Results of GitLab application Check
<details>
<summary>Expand for output related to the GitLab application check</summary>
<pre>
(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:check SANITIZE=true`)
(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true`)
(we will only investigate if the tests are passing)
</pre>
</details>
### Possible fixes
(If you can, link to the line of code that might be responsible for the problem)
issue