No branch to select when creating a merge request

Summary

This bug only comes up in GitLab Community Edition. There is only one options 'No matching results' to select in 'Merge Requests' page.

What is the current bug behavior

1. I changed the Preferred language in the setting [User Settings - Profile - Preferred language],from English to Chinese Simplifid.
2. I turn to 'Merge Requests' page, and try to merge a new branch to my current branch,but find no result to select.It happens in 'Source branch' and 'Target branch' selections.
3. I change the Preferred language back to English ,and the branches show as usual on the 'Merge Requests' page.
4. I try to change the Preferred language to the others,like Ruassian and Japanese,there is no result remains like Chinese languague.
5. I check 'Network' in my Chrome and find 1 http request to '/refs?search=&find=branches' gets wrong response JSON format.

Relevant logs and/or screenshots

• choosing English as Preferred language

• choosing Chinese as Preferred language

Results of GitLab environment info

Choosing English as Preferred language,the responese JSON like this:

{
    Branches: ["develop", "master"]
}

responese of Chinese preferred language:

{
    分支: ["develop", "master"]
}

response when choosing Japanese language:

{
    ブランチ: ["develop", "master"]
}