Xin LI c92bc5e996 Manually merge part of vendor import r238583 from Illumos.
Illumos changeset: 13680:2bd022a765e2
Illumos ZFS issue:

    2671 zpool import should not fail if vdev ashift has increased

MFC after:	3 days
2013-07-18 00:22:42 +00:00
..
2012-07-04 17:36:26 +00:00