"Add Existing Directory" forgets which folders were previously de-selected

If I import an existing project (non-qt, for example, Chromium sourcecode), and then choose some folders and decide not to select others, I have a project that has SOME but not all of the folders I wanted (because I made a mistake).

Later, I want to right click on the project and "add existing directory".
I get a dialog that lets me select and de-select folders again. However, it selects all top-level folders ignoring what I de-selected at project import time.