It's only used as a return value from group's or task's
setup handler. It instructs the running task tree on
how to proceed further.
It addresses the 21th point in the bugreport below.
Task-number: QTCREATORBUG-28741
Change-Id: I25802c76b9e7bc044c6a38197935798d2da9ad02
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: hjk <hjk@qt.io>