C++ ipv6_test does not detect IPv6 properly

ipv6_test uses

if ip -f inet6 -o addr | cut -f 9 -s -d' ' | grep global > /dev/null ; then
    echo "IPv6 addresses configured continuing"
else
    echo "No global IPv6 addresses configured - skipping test"
    exit 0
fi

to detect IPv6. On my system this returns false and IPv6 test does not run.

A naked './hello_world' then my broker sees a connection from ::1, the IPv6 localhost address. IPv6 is there, it works, and the system uses it.

Self test AclHost.cpp uses a different IPv6 detection method

bool haveIPv6(true);
try {
    sys::SocketAddress sa("::1", "");
    sa.firstAddress();
} catch (qpid::Exception) {
    haveIPv6 = false;
}

It creates a SocketAddress and uses it. If it can resolve "::1" then IPv6 is there.