A panel included in a tabbed panel, itself included on a dashboard is inaccurately reported as unused in the panel view.

Steps to reproduce the issue:

• Create an arbitrary panel
• Create a tabbed panel including the arbitrary panel
• Include this tabbed panel on a dashboard
• Visit the original panell page

Expected behavior: a link to the tabbed panel including it (and maybe the dashboards including the tabbed one).

Actual behavior "This panel does not appear on any dashboards."