I'ld like to programmatically trigger some very basic email notification when a new revision of a node is being created. I want to send a link to the compare page
But I wonder on which hook when saving a node do I have the old and the new vid available at once?
hook_node_presave() looks like a dead end to me.
This question is not specifically about D7. Though it's D7 I'm using right now, I'ld prefer to find a solution for both D7 and D8.