Segfault between QNetworkAccessManager and Q_GLOBAL_STATIC

#include <QStringList>
#include <QCoreApplication>

#include "private/qnetworkconfigmanager_p.h"
#include "private/qbearerengine_p.h"

struct HoldingType : public QObject
{
    HoldingType()
    {
        QNetworkConfigurationManagerPrivate *priv = qNetworkConfigurationManagerPrivate();

        QBearerEngine *engine = priv->engines()[0];

        QStringList keys = engine->accessPointConfigurations.keys();

        networkConfiguration.d = engine->accessPointConfigurations[keys[0]];
    }
    QNetworkConfiguration networkConfiguration;
};

class QSampleCache
{
public:
    QSampleCache()
        : t(0) { }
    ~QSampleCache()
    { delete t; }

    HoldingType* networkAccessManager()
    {
        if (!t)
            t = new HoldingType;
        return t;
    }
private:
    HoldingType *t;
};

Q_GLOBAL_STATIC(QSampleCache, sampleCache)

int main(int argc, char **argv)
{
  QCoreApplication app(argc, argv);

  sampleCache->networkAccessManager();
}

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7ae64d8 in QExplicitlySharedDataPointer<QNetworkConfigurationPrivate>::~QExplicitlySharedDataPointer (this=0x60b870, __in_chrg=<optimized out>)
    at ../../include/QtCore/../../../../../src/qtbase/src/corelib/tools/qshareddata.h:163
163         inline ~QExplicitlySharedDataPointer() { if (d && !d->ref.deref()) delete d; }
(gdb) bt
#0  0x00007ffff7ae64d8 in QExplicitlySharedDataPointer<QNetworkConfigurationPrivate>::~QExplicitlySharedDataPointer (this=0x60b870, __in_chrg=<optimized out>)
    at ../../include/QtCore/../../../../../src/qtbase/src/corelib/tools/qshareddata.h:163
#1  0x00007ffff7ae5a62 in QNetworkConfiguration::~QNetworkConfiguration (this=0x60b870, __in_chrg=<optimized out>) at /home/stephen/dev/src/qtbase/src/network/bearer/qnetworkconfiguration.cpp:227
#2  0x00007ffff7aa7df5 in QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate (this=0x60b7a0, __in_chrg=<optimized out>) at /home/stephen/dev/src/qtbase/src/network/access/qnetworkaccessmanager.cpp:1370
#3  0x00007ffff7aa7e82 in QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate (this=0x60b7a0, __in_chrg=<optimized out>) at /home/stephen/dev/src/qtbase/src/network/access/qnetworkaccessmanager.cpp:1381
#4  0x00007ffff6bdc814 in QScopedPointerDeleter<QObjectData>::cleanup (pointer=0x60b7a0) at ../../include/QtCore/../../../../../src/qtbase/src/corelib/tools/qscopedpointer.h:62
#5  0x00007ffff6bdae9d in QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::~QScopedPointer (this=0x60b788, __in_chrg=<optimized out>)
    at ../../include/QtCore/../../../../../src/qtbase/src/corelib/tools/qscopedpointer.h:98
#6  0x00007ffff6bd02f4 in QObject::~QObject (this=0x60b780, __in_chrg=<optimized out>) at /home/stephen/dev/src/qtbase/src/corelib/kernel/qobject.cpp:750
#7  0x00007ffff7aa5a9b in QNetworkAccessManager::~QNetworkAccessManager (this=0x60b780, __in_chrg=<optimized out>) at /home/stephen/dev/src/qtbase/src/network/access/qnetworkaccessmanager.cpp:475
#8  0x00007ffff7aa5ad2 in QNetworkAccessManager::~QNetworkAccessManager (this=0x60b780, __in_chrg=<optimized out>) at /home/stephen/dev/src/qtbase/src/network/access/qnetworkaccessmanager.cpp:490
#9  0x00000000004037fa in QSampleCache::~QSampleCache (this=0x606220 <(anonymous namespace)::Q_QGS_sampleCache::innerFunction()::holder>, __in_chrg=<optimized out>) at tst_qsound.cpp:20
#10 0x0000000000402f23 in (anonymous namespace)::Q_QGS_sampleCache::Holder::~Holder (this=0x606220 <(anonymous namespace)::Q_QGS_sampleCache::innerFunction()::holder>, __in_chrg=<optimized out>)
    at tst_qsound.cpp:37
#11 0x00007ffff600a121 in __run_exit_handlers (status=0, listp=0x7ffff638f6a8 <__exit_funcs>, run_list_atexit=run_list_atexit@entry=true) at exit.c:77
#12 0x00007ffff600a1a5 in __GI_exit (status=<optimized out>) at exit.c:99
#13 0x00007ffff5fefeac in __libc_start_main (main=0x402fe1 <main(int, char**)>, argc=1, ubp_av=0x7fffffffd678, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffd668)
    at libc-start.c:294
#14 0x0000000000401cf9 in _start ()

==11598== Memcheck, a memory error detector
==11598== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==11598== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==11598== Command: ./tst_qsound
==11598== 
==11598== Invalid read of size 8
==11598==    at 0x4ED04D8: QExplicitlySharedDataPointer<QNetworkConfigurationPrivate>::~QExplicitlySharedDataPointer() (in /home/stephen/dev/prefix/qtbase/lib/libQt5Network.so.5.2.0)
==11598==    by 0x4ECFA61: QNetworkConfiguration::~QNetworkConfiguration() (qnetworkconfiguration.cpp:227)
==11598==    by 0x4E91DF4: QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate() (qnetworkaccessmanager.cpp:1370)
==11598==    by 0x4E91E81: QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate() (qnetworkaccessmanager.cpp:1381)
==11598==    by 0x5EC2813: QScopedPointerDeleter<QObjectData>::cleanup(QObjectData*) (qscopedpointer.h:62)
==11598==    by 0x5EC0E9C: QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::~QScopedPointer() (qscopedpointer.h:98)
==11598==    by 0x5EB62F3: QObject::~QObject() (qobject.cpp:750)
==11598==    by 0x4E8FA9A: QNetworkAccessManager::~QNetworkAccessManager() (qnetworkaccessmanager.cpp:475)
==11598==    by 0x4E8FAD1: QNetworkAccessManager::~QNetworkAccessManager() (qnetworkaccessmanager.cpp:490)
==11598==    by 0x4037F9: QSampleCache::~QSampleCache() (tst_qsound.cpp:20)
==11598==    by 0x402F22: (anonymous namespace)::Q_QGS_sampleCache::innerFunction()::Holder::~Holder() (tst_qsound.cpp:37)
==11598==    by 0x68B4120: __run_exit_handlers (exit.c:77)
==11598==  Address 0xcdb0778 is not stack'd, malloc'd or (recently) free'd
==11598== 
==11598== 
==11598== Process terminating with default action of signal 11 (SIGSEGV)
==11598==  Access not within mapped region at address 0xCDB0778
==11598==    at 0x4ED04D8: QExplicitlySharedDataPointer<QNetworkConfigurationPrivate>::~QExplicitlySharedDataPointer() (in /home/stephen/dev/prefix/qtbase/lib/libQt5Network.so.5.2.0)
==11598==    by 0x4ECFA61: QNetworkConfiguration::~QNetworkConfiguration() (qnetworkconfiguration.cpp:227)
==11598==    by 0x4E91DF4: QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate() (qnetworkaccessmanager.cpp:1370)
==11598==    by 0x4E91E81: QNetworkAccessManagerPrivate::~QNetworkAccessManagerPrivate() (qnetworkaccessmanager.cpp:1381)
==11598==    by 0x5EC2813: QScopedPointerDeleter<QObjectData>::cleanup(QObjectData*) (qscopedpointer.h:62)
==11598==    by 0x5EC0E9C: QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::~QScopedPointer() (qscopedpointer.h:98)
==11598==    by 0x5EB62F3: QObject::~QObject() (qobject.cpp:750)
==11598==    by 0x4E8FA9A: QNetworkAccessManager::~QNetworkAccessManager() (qnetworkaccessmanager.cpp:475)
==11598==    by 0x4E8FAD1: QNetworkAccessManager::~QNetworkAccessManager() (qnetworkaccessmanager.cpp:490)
==11598==    by 0x4037F9: QSampleCache::~QSampleCache() (tst_qsound.cpp:20)
==11598==    by 0x402F22: (anonymous namespace)::Q_QGS_sampleCache::innerFunction()::Holder::~Holder() (tst_qsound.cpp:37)
==11598==    by 0x68B4120: __run_exit_handlers (exit.c:77)
==11598==  If you believe this happened as a result of a stack
==11598==  overflow in your program's main thread (unlikely but
==11598==  possible), you can try to increase the size of the
==11598==  main thread stack using the --main-stacksize= flag.
==11598==  The main thread stack size used in this run was 8388608.
==11598== 
==11598== HEAP SUMMARY:
==11598==     in use at exit: 38,731 bytes in 152 blocks
==11598==   total heap usage: 79,534 allocs, 79,382 frees, 4,805,467 bytes allocated
==11598== 
==11598== LEAK SUMMARY:
==11598==    definitely lost: 1,692 bytes in 23 blocks
==11598==    indirectly lost: 12,765 bytes in 14 blocks
==11598==      possibly lost: 5,392 bytes in 15 blocks
==11598==    still reachable: 18,882 bytes in 100 blocks
==11598==         suppressed: 0 bytes in 0 blocks
==11598== Rerun with --leak-check=full to see details of leaked memory
==11598== 
==11598== For counts of detected and suppressed errors, rerun with: -v
==11598== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
Segmentation fault (core dumped)