zfs: Fix cross-backend copies
zfs: Fix cross-backend copies

Without this change, copying a non-zfs container to a new container
that's backed by zfs was failing due to ContainerCreate already creating
the symlink and setting the permissions on the new path.

Reported-by: Brad Figg
Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

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