Disabled Select List options visible in Advanced Roadmaps plan scope

Disabled Select List options visible in Advanced Roadmaps plan scope.

Steps to reproduce

1. Create a custom field using the Select List field type and add several options in the field context.
2. Disable some of the options you've created.
3. Add the custom field to your Plan in Manage Custom Fields.
4. Open the drop-down options for the field from the Advanced roadmaps plan scope.

When user edits the issue or creates the issue, the custom field doesn't show the disabled option. Screenshot below. Issue only happens within Advanced Roadmaps plan scope. 

Expected Results

Disabled option shouldn't show in Advanced roadmaps plan scope.