Assignees cannot remove themselves from issues if they don't have edit access (BB-9536)
Someone forked my repo, and someone else accidentally created an issue there and assigned it to me. Unless I couldn't find the correct link, I can't remove myself as the assignee, probably because I don't have admin rights. If you're the assignee, you should at least be able to remove yourself as the assignee, especially when you remind me of that one issue every time I go to my dashboard ("Issues (1)").
Here's the issue: https://bitbucket.org/ef123/de4dot/issue/1/updated-crypto