I did just a quick test and it works. It really prevents the double parsing.
The downside is that for a big project mounted on slow sshfs it blocks the UI for a long time, which is not really usere friendly. Previously it blocked while still showing the open project dialog, so the user sees it's still loading. Now it opens the projects and then stalls, which would probably confuse people. It should be either splited into smaller parts or some visual indication of progress shoud be given.