The update-node-config man page contains the following paragraph, which is wrong and must be rewritten:
This subcommand can update only a node that is not enabled
for remote communication. A node that is enabled for commun-
ication over SSH must be updated by using the update-node-
ssh(1) subcommand. To determine whether a node is enabled
for communication over SSH, use the list-nodes(1) subcom-
In fact, update-node-config can be used on a node that is enabled for remote communication, but the node is no longer enabled for remote communication after the update. The paragraph should be rewritten to make this point clear.