QLibraryInfo version subgroups are not working

I have the following qt.conf:

[Paths]
Prefix=/foo

[Paths/4]
Prefix=/bar

[Paths/5]
Prefix=/baz

Now I copy qmake from both 4.8.5 and 5.2.1 into that folder and query the prefix:

./qmake -query QT_INSTALL_PREFIX; ./qmake-qt5 -query QT_INSTALL_PREFIX
/foo
/foo

This is not what the documentation of qt.conf says. Digging a bit in 4.8.5 lead to this patch that makes things work for me:

diff --git a/src/corelib/global/qlibraryinfo.cpp b/src/corelib/global/qlibraryinfo.cpp
index aa474a2..0fb90e6 100644
--- a/src/corelib/global/qlibraryinfo.cpp
+++ b/src/corelib/global/qlibraryinfo.cpp
@@ -361,6 +361,7 @@ QLibraryInfo::location(LibraryLocation loc)
 
         if(!key.isNull()) {
             QSettings *config = QLibraryInfoPrivate::configuration();
+            (void) config->childGroups();
             config->beginGroup(QLatin1String("Paths"));
 
             QString subKey;

./qmake-test -query QT_INSTALL_PREFIX
/bar

Of course the patch is nonsense, but it may show that something in QSettings is wrong.

Btw, one of the inline comments says:

if QT_VERSION is 6.0.2, then we use 'Paths/5'

but the API docs says

\o 6.0.2 matches \c Paths/6