Debug stacktrace of the issue:

(gdb) bt
#0  0xb7730424 in __kernel_vsyscall ()
#1  0xb6860aff in __GI_raise (sig=sig@entry=6)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#2  0xb6864083 in __GI_abort () at abort.c:90
#3  0xb689da95 in __libc_message (do_abort=do_abort@entry=2, 
    fmt=fmt@entry=0xb69a10d0 "*** Error in `%s': %s: 0x%s ***\n")
    at ../sysdeps/unix/sysv/linux/libc_fatal.c:199
#4  0xb68a87c2 in malloc_printerr (action=<optimized out>, 
    str=<optimized out>, ptr=0xb6da0463 <g_str_equal+35>) at malloc.c:4923
#5  0xb68a9510 in _int_free (av=0x8b000000, p=0xb6da045b <g_str_equal+27>, 
    have_lock=0) at malloc.c:3779
#6  0xb6db65d0 in g_free (mem=0xb6da0463 <g_str_equal+35>)
    at /build/buildd/glib2.0-2.38.1/./glib/gmem.c:197
#7  0xb6d943eb in g_datalist_clear (datalist=datalist@entry=0x8613790)
    at /build/buildd/glib2.0-2.38.1/./glib/gdataset.c:277
#8  0xb6e7f92e in g_object_finalize (object=0x8613788)
    at /build/buildd/glib2.0-2.38.1/./gobject/gobject.c:1024
#9  0xb746335c in gtk_widget_finalize (object=0x8613788)
    at /tmp/build/gtk+3/310/build-area/gtk+3.0-3.10.4/./gtk/gtkwidget.c:11515
#10 0xb6e80088 in g_object_unref (_object=0x8613788)
    at /build/buildd/glib2.0-2.38.1/./gobject/gobject.c:3197
#11 0xb6e8207f in g_object_run_dispose (object=object@entry=0x8613788)
---Type <return> to continue, or q <return> to quit---
    at /build/buildd/glib2.0-2.38.1/./gobject/gobject.c:1069
#12 0xb7463ff1 in gtk_widget_destroy (widget=0x8613788)
    at /tmp/build/gtk+3/310/build-area/gtk+3.0-3.10.4/./gtk/gtkwidget.c:4268
#13 0xb7338f00 in gtk_menu_shell_tracker_remove_func (position=0, 
    user_data=0x84b36c0)
    at /tmp/build/gtk+3/310/build-area/gtk+3.0-3.10.4/./gtk/gtkmenushell.c:2043
#14 0xb733bf15 in gtk_menu_tracker_remove_items (tracker=0xb5554f38, 
    tracker=0xb5554f38, n_items=1, offset=0, change_point=0xb555217c)
    at /tmp/build/gtk+3/310/build-area/gtk+3.0-3.10.4/./gtk/gtkmenutracker.c:257
#15 gtk_menu_tracker_model_changed (model=0x8643920, position=0, removed=1, 
    added=0, user_data=0xb5554f38)
    at /tmp/build/gtk+3/310/build-area/gtk+3.0-3.10.4/./gtk/gtkmenutracker.c:354
#16 0xb66043c6 in ffi_call_SYSV () at ../src/x86/sysv.S:65
#17 0xb660414b in ffi_call (cif=<optimized out>, cif@entry=0xbf956624, 
    fn=<optimized out>, rvalue=<optimized out>, avalue=<optimized out>, 
    avalue@entry=0xbf956550) at ../src/x86/ffi.c:411
#18 0xb6e7c129 in g_cclosure_marshal_generic (closure=0x862db70, 
    return_gvalue=0x0, n_param_values=4, param_values=0xbf956790, 
    invocation_hint=0xbf95673c, marshal_data=0x0)
---Type <return> to continue, or q <return> to quit---
    at /build/buildd/glib2.0-2.38.1/./gobject/gclosure.c:1454
#19 0xb6e7b8ae in g_closure_invoke (closure=0x862db70, 
    return_value=return_value@entry=0x0, n_param_values=4, 
    param_values=param_values@entry=0xbf956790, 
    invocation_hint=invocation_hint@entry=0xbf95673c)
    at /build/buildd/glib2.0-2.38.1/./gobject/gclosure.c:777
#20 0xb6e8ddf9 in signal_emit_unlocked_R (node=node@entry=0x8623680, detail=0, 
    instance=0x8643920, emission_return=emission_return@entry=0x0, 
    instance_and_params=0xbf956790)
    at /build/buildd/glib2.0-2.38.1/./gobject/gsignal.c:3586
#21 0xb6e95753 in g_signal_emit_valist (instance=instance@entry=0x8643920, 
    signal_id=signal_id@entry=266, detail=detail@entry=0, 
    var_args=0xbf956908 "\030UU\265", var_args@entry=0xbf9568fc "")
    at /build/buildd/glib2.0-2.38.1/./gobject/gsignal.c:3330
#22 0xb6e959e3 in g_signal_emit (instance=instance@entry=0x8643920, 
    signal_id=266, detail=detail@entry=0)
    at /build/buildd/glib2.0-2.38.1/./gobject/gsignal.c:3386
#23 0xb6fe1175 in g_menu_model_items_changed (model=0x8643920, 
    position=position@entry=0, removed=removed@entry=1, added=added@entry=0)
    at /build/buildd/glib2.0-2.38.1/./gio/gmenumodel.c:706
#24 0xb6fe4875 in g_dbus_menu_model_changed (added=0, removed=1, position=0, 
    items=0x0, proxy=<optimized out>)
    at /build/buildd/glib2.0-2.38.1/./gio/gdbusmenumodel.c:826
---Type <return> to continue, or q <return> to quit---
#25 g_dbus_menu_group_changed (group=0x86439a0, menu_id=0, position=0, 
    removed=1, added=0xb554b838)
    at /build/buildd/glib2.0-2.38.1/./gio/gdbusmenumodel.c:629
#26 0xb6fe4ff0 in g_dbus_menu_path_signal (connection=0x84a7810, 
    sender_name=0xb55054a8 ":1.17", 
    object_path=0xb553a760 "/com/canonical/indicator/datetime/desktop_greeter", interface_name=0xb554b428 "org.gtk.Menus", signal_name=0xb554a9f0 "Changed", 
    parameters=0xb554b778, user_data=0xb5554d38)
    at /build/buildd/glib2.0-2.38.1/./gio/gdbusmenumodel.c:292
#27 0xb6ffaf26 in emit_signal_instance_in_idle_cb (data=data@entry=0xb554ea00)
    at /build/buildd/glib2.0-2.38.1/./gio/gdbusconnection.c:3743
#28 0xb6dad5a0 in g_idle_dispatch (source=source@entry=0xb5520e00, 
    callback=0xb6ffae90 <emit_signal_instance_in_idle_cb>, 
    user_data=0xb554ea00) at /build/buildd/glib2.0-2.38.1/./glib/gmain.c:5250
#29 0xb6db083e in g_main_dispatch (context=0x847b598, context@entry=0x84a0a50)
    at /build/buildd/glib2.0-2.38.1/./glib/gmain.c:3065
#30 g_main_context_dispatch (context=context@entry=0x847b598)
    at /build/buildd/glib2.0-2.38.1/./glib/gmain.c:3641
#31 0xb6db0be8 in g_main_context_iterate (context=0x847b598, 
    block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/buildd/glib2.0-2.38.1/./glib/gmain.c:3712