Invalidate reverse dependencies to scheduled element with workspace
Description
Keys would change from one build to another. So building a second time an element depending a workspaced element, would fail to find the artifact that was already built.
Artifact cache would be populated with artifacts with the wrong key. This is a serious issue were an artifact that was built with a workspaced dependency would not rebuild after closing the workspace.
Elements depending on another element with workspace which has been scheduled should not have any keys until we have managed to built the workspaced element.
This merge request, when approved, will close issue/bug: #461 (closed)