Illumos #3745, #3811

3745 zpool create should treat -O mountpoint and -m the same
3811 zpool create -o altroot=/xyz -O mountpoint=/mnt ignores
     the mountpoint option
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Christopher Siden <christopher.siden@delphix.com>

References:
  https://www.illumos.org/issues/3745
  https://www.illumos.org/issues/3811
  illumos/illumos-gate@8b71377531

Ported-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1775

lib/libzfs/libzfs_pool.c

@@ -1159,7 +1159,6 @@ zpool_create(libzfs_handle_t *hdl, const char *pool, nvlist_t *nvroot,
 	nvlist_t *zc_fsprops = NULL;
 	nvlist_t *zc_props = NULL;
 	char msg[1024];
-	char *altroot;
 	int ret = -1;
 
 	(void) snprintf(msg, sizeof (msg), dgettext(TEXT_DOMAIN,
@@ -1260,21 +1259,6 @@ zpool_create(libzfs_handle_t *hdl, const char *pool, nvlist_t *nvroot,
 		}
 	}
 
-	/*
-	 * If this is an alternate root pool, then we automatically set the
-	 * mountpoint of the root dataset to be '/'.
-	 */
-	if (nvlist_lookup_string(props, zpool_prop_to_name(ZPOOL_PROP_ALTROOT),
-	    &altroot) == 0) {
-		zfs_handle_t *zhp;
-
-		verify((zhp = zfs_open(hdl, pool, ZFS_TYPE_DATASET)) != NULL);
-		verify(zfs_prop_set(zhp, zfs_prop_to_name(ZFS_PROP_MOUNTPOINT),
-		    "/") == 0);
-
-		zfs_close(zhp);
-	}
-
 create_failed:
 	zcmd_free_nvlists(&zc);
 	nvlist_free(zc_props);