Unassigned Issues will get Assigned when Editing the Issue

Steps to Reproduce

1. Allow Unassigned Issues in General Configuration set to ON.
2. Create a project with the Default Assignee set to Project Lead.
3. Create a new component with the assignee set to the Component Lead.
4. Create a new issue with Assignee set to Unassigned.
5. When the issue is created, the Assignee is Unassigned.
6. When you edit the issue, the Assignee field would be Automatic.
7. Upon saving the issue, the Assignee is now the Project Lead set in step 2.

Step 6 can be altered to include a component in the Component field, and upon saving the issue, the issue is assigned to the Component Lead if the Assignee field in the Edit Issue screen is left to Automatic.

Where can we see this problem?

Ideally, when a user creates an issue, he would like it to remain Unassigned. That includes editing the issue for any changes whatsoever. However, if he doesn't realise that the Assignee field in the Edit Issue screen is Automatic and saves the changes, it would assign the issue to the respective assignee (either the Project Lead or Component Lead).