When a contact is removed from groups, ref those groups' handles temporarily
When a contact is removed from groups, ref those groups' handles temporarily

Otherwise the group handles might disappear.

Ziemin/telepathy-gabble,jku/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,mlundblad/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,Ziemin/telepathy-gabble