Edit board can't change milestone gitlab

Summary

Can't change milestone when press "Edit" button in "Boards" screen.

Steps to reproduce

  1. Login in your account
  2. Access the Boards Screen: Issues -> Boards
  3. Press the button "Edit"
  4. Change the milestone

Example Project

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(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?

  1. Infinite load of dropdown (I believe that trying to search the milestones)
  2. If you click outside the button in the same screen (of Edit board) and try to change again, don't show any milestone

What is the expected correct behavior?

A list of milestones that already created.

Relevant logs and/or screenshots

image

Output of checks

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This bug happens on GitLab.com

Results of GitLab environment info

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`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

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(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)