REGRESSION: qt.pro no longer opens properly in Qt Creator

The qt.pro file in Qt 5.9.0 beta3 no longer opens properly in Qt Creator 4.2.2 (or 4.2.1, or possibly older versions of Qt Creator that I haven't tested):

• Most of the submodule folders appear empty in the Qt Creator project view.
• The "General Messages" pane contains the following:

  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(396): 'bypassNesting' is not a recognized test function.
  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(843): 'reload_properties' is not a recognized test function.
  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(857): 'bypassNesting' is not a recognized test function.
  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(91): Function 'prompt' is not implemented.
  (...repeated many times...)
  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(99): Ran into infinite loop (> 1000 iterations).
  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(209): Function 'prompt' is not implemented.
  (...repeated many times...)
  /Users/suitable/Desktop/Repositories/qt/qtbase/configure.pri(224): Ran into infinite loop (> 1000 iterations).
  ...
  Additional output omitted
  

Confirmed that Qt 5.8.0 opens correctly in both Qt Creator 4.2.1 and 4.2.2 (didn't test older versions of Qt Creator).

Confirmed that the failure happens when loading the qt.pro project in each of the following ways:

• Using the qt.pro.user file from the working 5.8.0 tree
• Deleting qt.pro.user and loading the Qt project from scratch by importing from the build directory

Qt build configuration used:

configure -debug -force-debug-info -developer-build -opensource -confirm-license -shared -platform macx-clang -no-openssl -nomake examples -nomake tests -no-compile-examples -no-icu -no-pch -no-framework -securetransport