feat(fs-lib): fsck_single can now handle PARTLABEL and PARTUUID

As an additional benefit, gentoo container now passing test-01.

modules.d/99fs-lib/fs-lib.sh

@@ -146,11 +146,7 @@ fsck_single() {
     local _drv
 
     [ $# -lt 2 ] && return 255
-    # if UUID= marks more than one device, take only the first one
-    [ -e "$_dev" ] || _dev=$(devnames "$_dev" | while read -r line || [ -n "$line" ]; do if [ -n "$line" ]; then
-        echo "$line"
-        break
-    fi; done)
+    _dev=$(readlink -f "$(label_uuid_to_dev "$_dev")")
     [ -e "$_dev" ] || return 255
     _fs=$(det_fs "$_dev" "$_fs")
     fsck_able "$_fs" || return 255