New "Parent" system field - Inconsistency of behavior on screens.

Issue Summary

The recently introduced "Parent" system field presents inconsistency in behavior. Consider the following situation on a Screen Scheme:

• The "Parent" field IS present on screen A mapped to the "Create issue" operation
• The "Parent" field IS present on a screen B mapped to the "View issue" operation
• The "Parent" field IS NOT present on the screen C mapped to the "Edit issue" operation

Since the field isn't present on screen C, for the issue types that use this screen scheme, it is expected that the "Parent" field can be edited during issue creation only, but not when clicking and editing an issue, however, what really happens is that the field is editable no matter what.

Steps to Reproduce

1. Create a new project, go to the Issue Type Screen scheme, and choose a Screen Scheme
2. On the chose Screen Scheme, edit screens so that each operation (Create/View/Edit) uses a different screen
3. Put the "Parent" system field on all screens
4. Adjust the Issue Layout to make the field visible, otherwise it will be hidden when empty
5. Try to edit the field on an existing issue (that uses that screen scheme), it should be editable, as it's expected
6. Now go to the screen mapped to the "Edit Issue" operation and remove the "Parent" field
7. Go to the same issue as before (refresh page) and try to edit the field, it will still be editable when it shouldn't

Expected Results

If a field is on a View and not on an Edit screen, the field should not be editable on existing issues

Actual Results

The field is on the View screen, but not on the Edit screen, but it is still editable

Workaround

No workaround available