message: hammer: trying to fix the sanitizer error
  Travis found an error with Clang 3.8's sanitizers, see Unfortunately, I cannot reproduce this error with clang version 6.0.0 (trunk 308825) locally. However, this seems to be an issue, because so far, we did not reset a value after moving from it.
diff: @@ -3281,6 +3281,7 @@ class parser
  while (true)
  {
  // parse value
  + value = value_t::discarded;
  parse_internal(keep, value);
  if (keep and not value.is_discarded())
  {
  