Subcategory permissions cannot be less restrictive than parent's

[supermathie (Michael Brown)]

@Jill_S

It won’t even let me change the name of the category, without giving me this error message.

This indictates the category was set up prior to us implementing this check: Subcategories do not inherit permissions from parent category - #22 by hellekin

To recover, ensure all permissions for the subcategory are first added to the parent.