API closes_issues endpoint fails when referencing external issues

We have identified an issue with the merge request API. 
Steps to reproduce it: 
- To have a GitLab project where JIRA service is active 
- To have a merge request in which description we include "Closes ABC-XXXX" 
- From the API: curl -H "PRIVATE-TOKEN: xxxxxxx" 
https://gitlab.example.com/api/v3/projects/XXX/merge_requests/YYY/closes_issues

It is expected the description of ABC-XXXX 
However, it returns: 
{"message":"500 Internal Server Error"}

In the server side, we see: 
NoMethodError (API::Entities::Issue missing attribute `description' on 
ABC-XXXX): 
/var/lib/git/gitlab/vendor/bundle/ruby/gems/grape-entity-0.4.8/lib/grape_entity/entity.rb:605:in 
`valid_exposure?' 
/var/lib/git/gitlab/vendor/bundle/ruby/gems/grape-entity-0.4.8/lib/grape_entity/entity.rb:551:in 
`value_for' 
/var/lib/git/gitlab/vendor/bundle/ruby/gems/grape-entity-0.4.8/lib/grape_entity/entity.rb:442:in 
`block in serializable_hash' 
/var/lib/git/gitlab/vendor/bundle/ruby/gems/grape-entity-0.4.8/lib/grape_entity/entity.rb:439:in 
`each' 
/var/lib/git/gitlab/vendor/bundle/ruby/gems/grape-entity-0.4.8/lib/grape_entity/entity.rb:439:in 
`each_with_object' 
/var/lib/git/gitlab/vendor/bundle/ruby/gems/grape-entity-0.4.8/lib/grape_entity/entity.rb:439:in 
`serializable_hash'

When using GitLab built-in issue tracker, this end-point works as expected. 
Do you manage to reproduce the problem?