Add the collected test items from a node

        Collection is complete once all nodes have submitted their
        collection.  In this case its pending list is set to an empty
        list.  When the collection is already completed this
        submission is from a node which was restarted to replace a
        dead node.  In this case we already assign the pending items
        here.  In either case ``.schedule()`` will instruct the
        node to start running the required tests.

def add_node_collection(self, node, collection):
        """Add the collected test items from a node

        Collection is complete once all nodes have submitted their
        collection.  In this case its pending list is set to an empty
        list.  When the collection is already completed this
        submission is from a node which was restarted to replace a
        dead node.  In this case we already assign the pending items
        here.  In either case ``.schedule()`` will instruct the
        node to start running the required tests.
        """
        assert node in self.node2pending
        if not self.collection_is_completed:
            self.node2collection[node] = list(collection)
            self.node2pending[node] = []
            if len(self.node2collection) >= self.numnodes:
                self.collection_is_completed = True
        elif self._removed2pending:
            for deadnode in self._removed2pending:
                if deadnode.gateway.spec == node.gateway.spec:
                    dead_collection = self.node2collection[deadnode]
                    if collection != dead_collection:
                        msg = report_collection_diff(
                            dead_collection,
                            collection,
                            deadnode.gateway.id,
                            node.gateway.id,
                        )
                        self.log(msg)
                        return
                    pending = self._removed2pending.pop(deadnode)
                    self.node2pending[node] = pending
                    break