"User not permitted" message when viewing a pull request

Summary

The message "User not permitted" is being displayed when accessing Bitbucket Server pull requests which has merge conflict whereby the source branch is from a forked repository and its target a branch in the main repository. This message is misleading and should either be changed or removed.

Steps to Reproduce

1. Create two users – bitbucket_user1 and bitbucket_user2
2. Create a project "X"
3. Create a repository "X"
4. Login with bitbucket_user1
5. Create a private fork for repository "X"
6. Make some change on the private fork repository
7. Send pull request for the fork repository to main repository with reviewer bitbucket_user2
8. Login with bitbucket_user2
9. See the pull request

Expected Results

The bitbucket_user2 can see the pull request without any warning.

Actual Results

"User not permitted" is shown although bitbucket_user2 can see the pull request closing the warning.

Notes

This symptom didn't occur on 5.0.0, and had been reported in BSERV-7052.

Workaround

Just click the "Close" in the warning and watch pull request.