Relative $ORIGIN in a zone file is resolved against the root instead of the current origin #431

Master resolves a relative name in a $ORIGIN directive against the root zone instead of against the current origin. The same applies to the optional origin argument of $INCLUDE.

RFC 1035, Section 5.1: "Domain names that do not end in a dot are called relative; the actual domain name is the concatenation of the relative part with an origin specified in a $ORIGIN, $INCLUDE, or as an argument to the master file loading routine." BIND appends the current origin to a relative $ORIGIN as well.

Steps to reproduce

String zone = "$ORIGIN sub\na 3600 IN A 192.0.2.1\n";
try (Master m = new Master(new ByteArrayInputStream(zone.getBytes()), Name.fromString("example.com."))) {
  System.out.println(m.nextRecord().getName());
}

Expected result

a.sub.example.com.

Actual result

a.sub.

Version: 3.7.1 and current master (9e26eba).