Fixed incorrect call to DestroyImage reported in #491.
MagickExport void SetImageInfoBlob(ImageInfo *image_info,const void *blob,
  const size_t length)
{
  assert(image_info != (ImageInfo *) NULL);
  assert(image_info->signature == MagickSignature);
  if (image_info->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
      image_info->filename);
  image_info->blob=(void *) blob;
  image_info->length=length;
}

MagickExport void SetImageInfoBlob(ImageInfo *image_info,const void *blob,
  const size_t length)
{
  assert(image_info != (ImageInfo *) NULL);
  assert(image_info->signature == MagickSignature);
  if (image_info->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
      image_info->filename);
  image_info->blob=(void *) blob;
  image_info->length=length;
}
