/usr/bin/software-properties-kde crashed when triggering mirror selection and clicking ok quickly

See https://docs.google.com/file/d/0B-ihXi2hkCPfMGlCbnpyU2syYXc/edit?pli=1

Backtrace:

#0 0x00007f3d0fd36fbd in poll () at ../sysdeps/unix/syscall-template.S:81
#1 0x00007f3d0c2b1fe4 in g_main_context_poll (priority=2147483647, n_fds=2, fds=0x7f3cf40034b0, timeout=-1, context=0x7f3cf40009c0) at /build/buildd/glib2.0-2.40.0/./glib/gmain.c:4028
#2 g_main_context_iterate (context=context@entry=0x7f3cf40009c0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/buildd/glib2.0-2.40.0/./glib/gmain.c:3729
#3 0x00007f3d0c2b20ec in g_main_context_iteration (context=0x7f3cf40009c0, may_block=1) at /build/buildd/glib2.0-2.40.0/./glib/gmain.c:3795
#4 0x00007f3d0c71b7be in QEventDispatcherGlib::processEvents (this=0x7f3cf40008e0, flags=...) at kernel/qeventdispatcher_glib.cpp:436
#5 0x00007f3d0c6ed0af in QEventLoop::processEvents (this=this@entry=0x7f3cf94e5e60, flags=...) at kernel/qeventloop.cpp:149
#6 0x00007f3d0c6ed3a5 in QEventLoop::exec (this=this@entry=0x7f3cf94e5e60, flags=...) at kernel/qeventloop.cpp:204
#7 0x00007f3d0c5e9c5f in QThread::exec (this=this@entry=0x2e52190) at thread/qthread.cpp:537
#8 0x00007f3d0c6ce823 in QInotifyFileSystemWatcherEngine::run (this=0x2e52190) at io/qfilesystemwatcher_inotify.cpp:265
#9 0x00007f3d0c5ec32f in QThreadPrivate::start (arg=0x2e52190) at thread/qthread_unix.cpp:349
#10 0x00007f3d10017182 in start_thread (arg=0x7f3cf94e6700) at pthread_create.c:312
#11 0x00007f3d0fd4430d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

Thread 1 (Thread 0x7f3d10428740 (LWP 4570)):
[KCrash Handler]
#6 QWidget::~QWidget (this=0x2dd66b0, __in_chrg=<optimized out>) at kernel/qwidget.cpp:1632
#7 0x00007f3d0b74abc9 in ?? () from /usr/lib/python3/dist-packages/PyQt4/QtGui.cpython-34m-x86_64-linux-gnu.so
#8 0x00007f3d0b70277e in ?? () from /usr/lib/python3/dist-packages/PyQt4/QtGui.cpython-34m-x86_64-linux-gnu.so
#9 0x00007f3d0bc0a486 in ?? () from /usr/lib/python3/dist-packages/sip.cpython-34m-x86_64-linux-gnu.so
#10 0x00007f3d0bc0b659 in ?? () from /usr/lib/python3/dist-packages/sip.cpython-34m-x86_64-linux-gnu.so
#11 0x000000000046bbe2 in subtype_dealloc.16050 (self=0x7f3d0128c708) at ../Objects/typeobject.c:1172
#12 0x0000000000431980 in dict_dealloc.9974 (mp=0x7f3d0ed50bc8) at ../Objects/dictobject.c:1383
#13 0x000000000046bce9 in subtype_dealloc.16050 (self=0x7f3d01293b00) at ../Objects/typeobject.c:1157
#14 0x0000000000454b2b in insertdict.10035 (mp=mp@entry=0x7f3d1038a348, key=key@entry=0x7f3d102a9848, hash=2785936968932569566, value=0x9def60 <_Py_NoneStruct>) at ../Objects/dictobject.c:823
#15 0x0000000000454dca in PyDict_SetItem (op=op@entry=0x7f3d1038a348, key=key@entry=0x7f3d102a9848, value=<optimized out>) at ../Objects/dictobject.c:1207
#16 0x00000000004ac48a in _PyModule_ClearDict (d=0x7f3d1038a348) at ../Objects/moduleobject.c:353
#17 0x00000000005bf6ed in _PyModule_Clear (m=0x7f3d103894a8) at ../Objects/moduleobject.c:304
#18 PyImport_Cleanup () at ../Python/import.c:515
#19 0x00000000005bf945 in Py_Finalize.part.6.32879 () at ../Python/pythonrun.c:616
#20 0x00000000005bfc7c in Py_Finalize () at ../Python/pythonrun.c:2714
#21 Py_Exit (sts=sts@entry=0) at ../Python/pythonrun.c:2712
#22 0x000000000041e5d9 in handle_system_exit.part.7 () at ../Python/pythonrun.c:1811
#23 0x00000000005bffc3 in handle_system_exit () at ../Python/pythonrun.c:1856
#24 PyErr_PrintEx (set_sys_last_vars=set_sys_last_vars@entry=1) at ../Python/pythonrun.c:1821
#25 0x000000000060c170 in PyErr_Print () at ../Python/pythonrun.c:1717
#26 PyRun_SimpleFileExFlags (fp=fp@entry=0x2588900, filename=<optimized out>, filename@entry=0x7f3d102a2cb0 "/usr/bin/software-properties-kde", closeit=closeit@entry=1, flags=flags@entry=0x7fff07fa85d0) at ../Python/pythonrun.c:1610
#27 0x000000000060d3ac in PyRun_AnyFileExFlags (flags=0x7fff07fa85d0, closeit=<optimized out>, filename=<optimized out>, fp=0x2588900) at ../Python/pythonrun.c:1292
#28 run_file (p_cf=0x7fff07fa85d0, filename=0x2520200 L"/usr/bin/software-properties-kde", fp=0x2588900) at ../Modules/main.c:319
#29 Py_Main (argc=argc@entry=5, argv=argv@entry=0x251e010) at ../Modules/main.c:751
#30 0x000000000041ec0d in main (argc=5, argv=<optimized out>) at ../Modules/python.c:69

Despite having -dbg or if not available -dbgsy packages of the package containing /usr/lib/python3/dist-packages/sip.cpython-34m-x86_64-linux-gnu.so (its python3-sip) and /usr/lib/python3/dist-packages/PyQt4/QtGui.cpython-34m-x86_64-linux-gnu.so (its python3-pyqt4) (found via apt-file) I still get ?? ... normally this should not happen ...

Furthermore I noticed that I can install both, python3.4-dbgsym and python3.4-dbg which should normally conflict and also python-qt4-dbg and python-qt4-dbgsym can be installed in paralell ... how is this possible? (Anyway the backtrace does not become better)

Steps to Reproduce:
It does not happen every time, but it will happen for sure if you repeat the following steps if it does not crash (and you have to press "Ok" pretty quick)

1. Open "Configure Software Sources" in Moun
2. Trigger the mirror drop down and hover over the options
3. Press "ok" after loosing the focus of the dropdown