correct error in sliver.__unicode__ if slice deleted before sliver
correct error in sliver.__unicode__ if slice deleted before sliver

cboling/xos,zdw/xos,opencord/xos,open-cloud/xos,cboling/xos,open-cloud/xos,cboling/xos,open-cloud/xos,cboling/xos,cboling/xos,zdw/xos,opencord/xos,zdw/xos,opencord/xos,zdw/xos