NAK causes n_dhcp4_client_lease_select failure

[gotthardp]

When the client is in STATE_RENEWING, there is a (current) probe->current_lease.
Now, when a NAK arrives the state changes (in n_dhcp4_client_probe_transition_nak) to STATE_INIT, retaining the current lease.
Then, once the DISCOVER-OFFER-REQUEST-ACK dance is over, the n_dhcp4_client_lease_select gets called. It checks the probe->current_lease is (still) not NULL and fails. The probe is not able to recover from this.

I wonder-- shouldn't be the probe->current_lease cleared in n_dhcp4_client_probe_transition_nak just like it is cleared in n_dhcp4_client_probe_transition_lifetime? Or should the custom code unref it prior calling the n_dhcp4_client_lease_select? (I will create a PR if you confirm this is a bug to be fixed here.)

[bengal]

Good catch, this was fixed in e4af932.