Handle multiple callbacks having the same destroy
@gregier
Submitted by Garrett Regier Link to original bug (#752252)
Description
This can be seen with API like g_object_bind_property_full() and is fairly annoying to work around. Currently this causes an abort/fail because the closure is being freed too many times.
I looked into the closure code and it turns out it is fairly easy to support and a patch with a test is incoming.