It's only in RFC 2980 (not 977 or 3977), but Net::NNTP has
supported it since 2001, at least. We'll be making changes
to avoid pathological behavior, so test it, first.
'cross newsgroup BODY by Message-ID');
ok($n->head('<testmessage@example.com>'),
'cross newsgroup HEAD by Message-ID');
+ is($n->xpath('<testmessage@example.com>'), 'x.y.z/1', 'xpath hit');
+ is($n->xpath('<non-existent@example.com>'), undef, 'xpath miss');
# pipelined requests:
{