poudriere jails accidentally broken

Hi,

I was a bit too zealous in deleting some snapshots
and deleted ones like this:

ssd/poudriere/jails/14S-amd64@clean

Now, that jail won't run - this happens:

ssd/poudriere/jails/14S-amd64@clean': dataset does not exist

when I try to run it. If the jail is updated with "poudriere jail
-j jailname -u", the @clean gets made somewhere in the process
and it works again. But this means that all the ports the jail has 
already built get re-built from scratch.

Is there a way to re-create the '@clean' without having to rebuild
all the ports? I realise this is my own idiot fault, and that the answer
to this is probably "no", but I thought I'd ask here first.
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