Issue Summary

When a sprint is closed but it still have open issues, then the issues go back to backlog (or a new sprint). If an user tries editing the sprint field on one of these issues, he has the option to add a new value but he can't remove the closed sprint. When the sprint field is edited through 'Bulk Operation' (Edit or Move), the closed sprint is removed from the field and so a new value is added instead of keeping both.

Steps to Reproduce

1. Create a sprint
2. Create an issue and add it to the sprint
3. Close the sprint and move open issues to backlog
4. Open the issue created on step 2 and try editing sprint field
5. You won't be able to remove sprint created on step 1 however you'll be able to add a new sprint
6. Run a search that returns that issue, then choose Tools > Bulk Change > Select the issue
7. Choose Edit option then enter a new value for sprint field
8. Open the issue created on step 2, there'll see the sprint created on step 1 is no longer shown on sprint field

Expected Results

Issue should keep closed sprint information.

Actual Results

The value of sprint field is replaced.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available