QProcess::execute hangs on OS X 10.12.2 built with newest XCode 8.2.1

Qt 5.7.1 built with Xcode 8.2 had no issues, but after updating the OS to 10.12.2 and XCode to 8.2.1 and rebuilding Qt QProcess::execute often hangs in waitForProcessFinished even though the process it has executed has already finished. Here's the callstack I am seeing here where it has hung and I've paused it:

1 poll 0x7fffa8ff0232
2 qt_ppoll(pollfd *, unsigned int, timespec const *) qcore_unix.cpp 83 0x100ee7cfb
3 qt_safe_poll(pollfd *, unsigned int, timespec const *) qcore_unix.cpp 102 0x100ee7bfe
4 qt_poll_msecs(pollfd *, unsigned int, int) qcore_unix_p.h 353 0x100e05721
5 (anonymous namespace)::QProcessPoller::poll(int) qprocess_unix.cpp 164 0x100e05a1e
6 QProcessPrivate::waitForFinished(int) qprocess_unix.cpp 871 0x100e05db6
7 QProcess::waitForFinished(int) qprocess.cpp 1922 0x100d9982b
8 QProcess::execute(QString const&, QStringList const&) qprocess.cpp 2428 0x100d9b44b
9 MainWindow::on_runTestButton_clicked() mainwindow.cpp 30 0x100007c0c
10 MainWindow::qt_static_metacall(QObject *, QMetaObject::Call, int, void * *) moc_mainwindow.cpp 71 0x100008ad8
11 MainWindow::qt_metacall(QMetaObject::Call, int, void * *) moc_mainwindow.cpp 104 0x100008c55
12 QMetaObject::metacall(QObject *, QMetaObject::Call, int, void * *) qmetaobject.cpp 301 0x100e71b8d
13 QMetaObject::activate(QObject *, int, int, void * *) qobject.cpp 3755 0x100ead7e0
14 QMetaObject::activate(QObject *, QMetaObject const *, int, void * *) qobject.cpp 3602 0x100eacb3d
15 QAbstractButton::clicked(bool) moc_qabstractbutton.cpp 310 0x1001f515b
16 QAbstractButtonPrivate::emitClicked() qabstractbutton.cpp 411 0x1001f5042
17 QAbstractButtonPrivate::click() qabstractbutton.cpp 404 0x1001f4eb1
18 QAbstractButton::mouseReleaseEvent(QMouseEvent *) qabstractbutton.cpp 1009 0x1001f6432
19 QWidget::event(QEvent *) qwidget.cpp 8785 0x10011727d
20 QAbstractButton::event(QEvent *) qabstractbutton.cpp 966 0x1001f6213
... <More>

I have attached a small test project that hits the issue here but it doesn't hit the issue every time.

I am able and willing to test any changes to Qt itself as I am using a 5.7.1 release built locally.

thanks,
Jeremy