create_root_pool: always create ESP

[tsoome]

No description provided.

[pyhalov]

<leoric> tsoome: on boot I get warning about zfs unable to find rpool1 (installing over already installed system). Also zpool sees 256MB as expandsz, which looks strange
<leoric> (can't read MOS of pool rpool1)
<leoric> did zpool create -B preserve some old labels?
<leoric> should we do something like zpool labelclear disk || true for every disk?
<leoric> or should loader be more clever about zfs labels? 
<leoric> reinstalling over this system doesn't help

[tsoome]

Yes, we need to use labelclear on ESP to make sure we do not have any leftovers there.