Loading a session with multiple projects may leave one project unconfigured

Steps to reproduce:

• Have multiple Kits configured
• Have a session with at least two projects (the first one needs to be a qmake project, the second one a generic project)
• Make sure both projects are set up properly
• Close Creator
• Delete the .creator.user for the first project (I did delete the shadow-build directory too)
• Open Creator, load the session
• The "Project Setup" page for the first project appears, but hides after a few seconds
• The first project is unconfigured now, all build actions are grayed out and the spinner in the Projects side pane spins forever

It seems others have hit that too:

• https://forum.qt.io/topic/104597/add-new-add-existing-files-add-existing-directory-all-greyed-out-in-a-qmake-project-episode-2
• https://forum.qt.io/topic/87315/add-new-add-existing-files-add-existing-directory-all-greyed-out-in-a-qmake-project