Importing project with closed/merged MRs from forks creates additional branches

Summary

Importing project with closed/merged MRs from forks creates additional branches

What is the current bug behavior?

Source branches from MRs that were closed still end up being created

What is the expected correct behavior?

Source branches from MRs that were closed are ignored

Output of checks

This bug happens on GitLab.com

Possible fixes

I think we might need to add a check for the MR state in https://gitlab.com/gitlab-org/gitlab/blob/bf490f3d50512d2e6e741535736c2a2d5ed40605/lib/gitlab/import_export/merge_request_parser.rb#L42 before creating the branches?