Projects Rest API search issue

Description of the problem

Projects Rest API search capability does not work as expected/documented.

Which Group/Project (with full path) is experiencing the issue?

This issue is reproducible on any multi-level namespace project for both, public https://gitlab.com and enterprise private instance running 10.1.4-ee a5120549

Approximate date/time when the error occurred.

It can be reproduced any time by accessing projects Rest API.

Describe what you were doing right before the issue occurred.

I search for a specific project in gitlab.com using Rest API as per official documentation:
https://docs.gitlab.com/ee/api/projects.html#list-all-projects

Also making sure the namespace path encoding is respected as described in:
https://docs.gitlab.com/ce/api/README.html#namespaced-path-encoding

For instance, the following curl command returns nothing.

curl -s -u <username> GET "https://gitlab.com/api/v4/projects?search=gitlab-org%2Fdesign.gitlab.com"

At the same time when I search for a keyword with no "/" it finds exact same project which I cannot get earlier:

curl -s -u <username> GET "https://gitlab.com/api/v4/projects?search=design.gitlab.com"  | jq
Enter host password for user '<username>':
[
  {
    "id": 4456656,
    "description": "design guidelines and UI components for GitLab CE/EE\r\n\r\nhttps://gitlab-org.gitlab.io/design.gitlab.com/",
    "default_branch": "master",
    "tag_list": [],
    "ssh_url_to_repo": "git@gitlab.com:gitlab-org/design.gitlab.com.git",
    "http_url_to_repo": "https://gitlab.com/gitlab-org/design.gitlab.com.git",
    "web_url": "https://gitlab.com/gitlab-org/design.gitlab.com",
    "name": "design.gitlab.com",
    "name_with_namespace": "GitLab.org / design.gitlab.com",
    "path": "design.gitlab.com",
    "path_with_namespace": "gitlab-org/design.gitlab.com",
    "avatar_url": null,
    "star_count": 1,
    "forks_count": 0,
    "created_at": "2017-10-23T07:42:02.608Z",
    "last_activity_at": "2017-11-21T08:26:02.675Z"
  }
]

The same is reproducible in the browser with or without path encoding; I expect the browser to do automatic encoding still both do not work:

https://gitlab.com/api/v4/projects?search=design.gitlab.com (works as expected)
https://gitlab.com/api/v4/projects?search=gitlab-org/design.gitlab.com (doesn't work)
https://gitlab.com/api/v4/projects?search=gitlab-org%2Fdesign.gitlab.com (doesn't work)

Edited by Vladimir Cantiru