iotests: Do not rely on unavailable domains in 162

iotests: Do not rely on unavailable domains in 162

There are some (mostly ISP-specific) name servers who will redirect
non-existing domains to special hosts. In this case, we will get a
different error message when trying to connect to such a host, which
breaks test 162.

162 needed this specific error message so it can confirm that qemu was
indeed trying to connect to the user-specified port. However, we can
also confirm this by setting up a local NBD server on exactly that port;
so we can fix the issue by doing just that.

Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>