Avoiding repeated PVD read attempts if first reading of PVD yielded error

libisoburn/isoburn.c

@@ -135,6 +135,7 @@ int isoburn_new(struct isoburn **objpt, int flag)
  o->truncate= 0;
  o->iso_source= NULL;
  o->fabricated_disc_status= BURN_DISC_UNREADY;
+ o->media_read_error= 0;
  o->toc= NULL;
  o->wrote_well= -1;
  o->loaded_partition_offset= 0;