Try to unsubscribe from the proxy used for subscription
Try to unsubscribe from the proxy used for subscription

This makes cancel much cleaner and solves a problem
where we were trying to use a previously disposed proxy.

https://bugzilla.gnome.org/show_bug.cgi?id=683985

xkahn/gvfs-cmis,philipl/gvfs,gicmo/gvfs,philipl/gvfs,xkahn/gvfs-cmis,halfline/gvfs,xkahn/gvfs-cmis,halfline/gvfs,gicmo/gvfs,philipl/gvfs,gicmo/gvfs,halfline/gvfs,gicmo/gvfs,xkahn/gvfs-cmis