kiss: Safeguard against su removal

kiss

@@ -927,10 +927,16 @@ pkg_remove() {
             required_by="$required_by'${file##*/}', "
     done
 
+    [ "$required_by" ] &&
+        die "$1" "Package is required by ${required_by%, }"
+
     # Disable globbing.
     set -f
 
-    [ "$required_by" ] && die "$1" "Package is required by ${required_by%, }"
+    # Ensure that the user leaves their machine in a working state by
+    # refusing to remove the package which providees 'su'.
+    grep -q "^$(command -v su)$" "$sys_db/$1/manifest" &&
+        die "$1" "Removing su will break the system."
 
     # Block being able to abort the script with 'Ctrl+C' during removal.
     # Removes all risk of the user aborting a package removal leaving