Let ISO size cover appended partitions if --protective-msdos-label or nonzero -partition_offset is given

libisofs/system_area.c

@@ -2153,6 +2153,14 @@ int iso_write_system_area(Ecma119Image *t, uint8_t *buf)
         }
     }
 
+    if ((((t->system_area_options >> 2) & 0x3f) == 0 &&
+         (t->system_area_options & 3) == 1) ||
+        t->opts->partition_offset > 0) {
+        /* Protective MBR || partition offset */
+        /* ISO will not be a partition. It can span the whole image. */
+        t->pvd_size_is_total_size = 1;
+    }
+
     return ISO_SUCCESS;
 }