Hang on startup

[Andrew Goodbody]

Digikam 5.8.0 built from source on Debian testing. It hangs on startup, 
no splash screen seen, have left it for hours with no change. Used to 
start up OK.
Log from gdb session. Had to press Ctrl-C to get attention.

$ gdb digikam
GNU gdb (Debian 7.12-6+b1) 7.12.0.20161007-git
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
<http://gnu.org/licenses/gpl.html>
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Reading symbols from digikam...done.
(gdb) run
Starting program: /usr/bin/digikam
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffacfcb700 (LWP 2840)]
[New Thread 0x7fffac7ca700 (LWP 2841)]
[New Thread 0x7fffaa4a6700 (LWP 2842)]
[New Thread 0x7fffa3fff700 (LWP 2843)]
[New Thread 0x7fffa37fe700 (LWP 2844)]

(digikam:2800): GLib-GObject-WARNING **: cannot register existing type 
'GtkWidget'

(digikam:2800): GLib-GObject-CRITICAL **: g_type_add_interface_static: 
assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed

(digikam:2800): GLib-GObject-WARNING **: cannot register existing type 
'GtkBuildable'

(digikam:2800): GLib-GObject-CRITICAL **: 
g_type_interface_add_prerequisite: assertion 'G_TYPE_IS_INTERFACE 
(interface_type)' failed

(digikam:2800): GLib-CRITICAL **: g_once_init_leave: assertion 'result 
!= 0' failed

(digikam:2800): GLib-GObject-CRITICAL **: g_type_add_interface_static: 
assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed

(digikam:2800): GLib-GObject-CRITICAL **: g_type_register_static: 
assertion 'parent_type > 0' failed
^C
Thread 1 "digikam" received signal SIGINT, Interrupt.
syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
38	../sysdeps/unix/sysv/linux/x86_64/syscall.S: No such file or directory.
(gdb) bt
#0  0x00007fffe3035da9 in syscall () at 
../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
#1  0x00007fffe2ab46df in g_cond_wait () at 
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fffe2a967b7 in g_once_init_enter () at 
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fffa9068495 in gtk_buildable_get_type ()
     at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#4  0x00007fffa9097217 in gtk_container_get_type ()
     at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#5  0x00007fffa9063ffd in gtk_bin_get_type ()
     at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#6  0x00007fffa90922cc in gtk_combo_box_get_type ()
     at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#7  0x00007fffa909533c in gtk_combo_box_entry_get_type ()
     at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#8  0x00007fffa9095489 in gtk_combo_box_entry_new ()
     at /usr/lib/x86_64-linux-gnu/libgtk-x11-2.0.so.0
#9  0x00007fffa29d1210 in  ()
     at /usr/lib/x86_64-linux-gnu/qt5/plugins/styles/libqgtk2style.so
#10 0x00007fffa29d246b in  ()
     at /usr/lib/x86_64-linux-gnu/qt5/plugins/styles/libqgtk2style.so
#11 0x00007fffe73541c3 in QStyleFactory::create(QString const&) ()
     at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#12 0x00007fffe72ea04a in QApplication::style() ()
     at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#13 0x00007fffe72ea39d in QApplicationPrivate::initialize() ()
     at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#14 0x00007fffe72ea3f4 in QApplicationPrivate::init() ()
     at /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#15 0x000055555555a02e in main(int, char**) (argc=1, argv=0x7fffffffe278)
     at /home/ag/src/dk5/core/app/main/main.cpp:70
(gdb)