Comment 1 for bug 745002

valgrind error:

"==26119== at 0x63CAE71: raise (raise.c:64)
==26119== by 0x63CE34D: abort (abort.c:92)
==26119== by 0x61D239F: g_assertion_message (gtestutils.c:1358)
==26119== by 0x61D297C: g_assertion_message_expr (gtestutils.c:1369)
==26119== by 0x8162243: editing_host_page_replace_photo (PhotoPage.c:3929)
==26119== by 0x816CC44: library_photo_page_display_for_collection (PhotoPage.c:9355)
==26119== by 0x8207AA9: library_window_switch_to_photo_page (LibraryWindow.c:5117)
==26119== by 0x8142BD7: collection_page_real_on_item_activated (CollectionPage.c:2667)
==26119== by 0x8178B44: checkerboard_page_real_on_left_released (Page.c:5398)
==26119== by 0x5A11963: _gtk_marshal_BOOLEAN__BOXED (gtkmarshalers.c:86)
==26119== by 0x611C371: g_closure_invoke (gclosure.c:767)
==26119== by 0x612F047: signal_emit_unlocked_R (gsignal.c:3252)
==26119== by 0x61378D6: g_signal_emit_valist (gsignal.c:2993)
==26119== by 0x6137CC1: g_signal_emit (gsignal.c:3040)
==26119== by 0x5B46555: gtk_widget_event_internal (gtkwidget.c:4988)
==26119== by 0x5A0FAEC: gtk_propagate_event (gtkmain.c:2493)
==26119== by 0x5A0FE4E: gtk_main_do_event (gtkmain.c:1683)
==26119== by 0x5D5CA09: gdk_event_dispatch (gdkevents-x11.c:2377)
==26119== by 0x61AAAA7: g_main_context_dispatch (gmain.c:2440)
==26119== by 0x61AB26F: g_main_context_iterate.clone.5 (gmain.c:3091)
==26119== by 0x61AB92A: g_main_loop_run (gmain.c:3299)
==26119== by 0x5A0EB98: gtk_main (gtkmain.c:1255)
==26119== by 0x8297003: application_start (Application.c:141)
==26119== by 0x813931E: library_exec (main.c:1092)
==26119== by 0x813A6FE: _vala_main (main.c:1553)
==26119== by 0x813A7FB: main (main.c:1569)"