nixos/stage-1: follow mount options

For fileSystems needed for boot which are bind mounts, busybox tend to
ignore mount options, so we remount right afterwards

nixos/modules/system/boot/stage-1-init.sh

@@ -410,6 +410,11 @@ mountFS() {
         n=$((n + 1))
     done
 
+    # For bind mounts, busybox has a tendency to ignore options, which can be a
+    # security issue (e.g. "nosuid"). Remounting the partition seems to fix the
+    # issue.
+    mount "/mnt-root$mountPoint" -o "remount,$optionsPrefixed"
+
     [ "$mountPoint" == "/" ] &&
         [ -f "/mnt-root/etc/NIXOS_LUSTRATE" ] &&
         lustrateRoot "/mnt-root"