Comment 2 for bug 838812

StacktraceTop:
 type_check_is_value_type_U (type=17508004033650307960) at /build/buildd/glib2.0-2.29.16/./gobject/gtype.c:4084
 g_type_check_value (value=0x7fe71c1addc8) at /build/buildd/glib2.0-2.29.16/./gobject/gtype.c:4126
 gst_value_init_and_copy (dest=0x7ffffa5eaf98, src=0x7fe71c1addc8) at gstvalue.c:3854
 gst_structure_copy (structure=0x23b6240) at gststructure.c:312
 boxed_proxy_collect_value (collect_values=<optimized out>, value=0x7ffffa5eb058, n_collect_values=<optimized out>, collect_flags=<optimized out>) at /build/buildd/glib2.0-2.29.16/./gobject/gboxed.c:225