make create permission of plus cards inherit from update of root
Ticket
+commit
+issues
This issue came up on connectipedia.org with User cards.
Typical users (anyone signed in) did not have permission to create User cards directly, but they did have permission to edit them. Since plus card create permissions inherited from root cards, that meant they couldn't create plus cards.
So, for example, if Mike+wall existed, they could edit that, but if it didn't, they couldn't create it.
+solution
Conceptually, creating Mike+wall is really more akin to updating Mike than creating it. So, for now, I think we should interpret "_left" on create permissions to inherit Mike's "update" permission, not its create permission. (We may later make that more configurable.) We should also spell this out in the interface.