Epic links to add child epic includes itself

Summary

When in Epic&1's tree view and I click "Add an epic", the list includes Epic&1.

Steps to reproduce

Assuming target Epic with iid&1 within a group...

  • Go to an epic's "Epics and Issues" view for Epic&1
  • Type in &1
  • The epic may be included in this list (depending on the number other epics)

Example Project

(If possible, please create an example project here on GitLab.com that exhibits the problematic behavior, and link to it here in the bug report)

(If you are using an older version of GitLab, this will also determine whether the bug is fixed in a more recent version)

What is the current bug behavior?

The epic itself is included in the list of possible child epics.

What is the expected correct behavior?

The epic itself should never be included in the list of possible child epics.

Relevant logs and/or screenshots

Locally:

image

On production (gitlab-com&107):

image

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info 
(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)

Results of GitLab application Check

Expand for output related to the GitLab application check 
(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)

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)