kea/tests/lettuce/configurations/DO_NOT_USE_127.0.0.1:47807

Note well:

In some configuration we intentionally use an IPv6 address (::1) with
port 47807.  DO NOT CHANGE THAT; at least do not change it to
127.0.0.1:47807.  See git e3f4b290d17a68db728166cdffcbe93517966e8b
for why.