net/mtr broken without ipv6

[Lena at lena.kiev.ua]

> > > I build my custom kernel without IPv6 since I'm not going to be using
> > > it any time soon. The mtr port doesn't work anymore

> > Downgrade the mtr port to mtr-nox11-0.82_1.

> > I update ports tree with `portsnap` and use `svn export`
> > (devel/subversion port) for downgrading a single port.

> I don't see how downgrading will fix it unless this is a newly introduced
> bug

It is. 0.82 works, 0.84 doesn't.
https://bugs.launchpad.net/mtr/+bug/1130561

> however you can also use ports-mgmt/portdowngrade.

portdowngrade also uses subversion, but not "export".
I suspect that combination of portdowngrade with portsnap can cause problems.