Boot environments and zfs canmount=noauto

I'm trying to follow Michael Dexter's post about using bhyve with boot
environments.  It involves moving all child datasets under
zroot/ROOT/default, so that you can have entirely independent systems.

http://callfortesting.org/bhyve-boot-environments/

> Let's change the datasets with "canmount on" to "canmount noauto":
> [snip]
> Considering that this setting is harmless to a system with a single
> boot environment, I would not object to it being the default. Hint
> hint. 

When I set all the datasets with canmount=on to canmount=noauto, only
zroot/ROOT/default gets mounted on next boot.  It's my understanding
that 'zfs mount -a' doesn't mount datasets with canmount=noauto, but if
I leave them with canmount=on, they will try to mount regardless of
which BE is active.

I'm trying this with 11.0-BETA2.  Can sometime tell me what I'm missing?