It may be another bug, as you're still able to trigger compiz shortcuts but it's possible that you're able to switch desktops because it's a keyboard+mouse shortcuts. Does other compiz keyboard only shortcuts work when you close the last window on the current workspace ?
I currently can't reproduce it on my desktop machine, but I does not necessarily means it's been fixed as I still can't figure out what is triggering this bug in the first place.
It may be another bug, as you're still able to trigger compiz shortcuts but it's possible that you're able to switch desktops because it's a keyboard+mouse shortcuts. Does other compiz keyboard only shortcuts work when you close the last window on the current workspace ?
I currently can't reproduce it on my desktop machine, but I does not necessarily means it's been fixed as I still can't figure out what is triggering this bug in the first place.