[Samba] samba-tool does not export SPNs

[banda bassotti]

Hello, I added two separate spn to two accounts, then I tried to export
them to the keytab but it doesn't seem to work. with the command below:

$ samba-tool spn list z1
z1
User CN = z1, CN = Users, DC = home, DC = lan has the following
servicePrincipalName:
          zookeeper/ap42.home.lan at HOME.LAN

$ klist -k -e z1.keytab
Keytab name: FILE: test.keytab
KVNO Principal
---- ----------------------------------------------
----------------------------
    2 z1 at HOME.LAN (aes256-cts-hmac-sha1-96)

and so on for the other algorithms

trying to export also the spn:

$ samba-tool domain exportkeytab z1.keytab
--principal=zookeeper/ap42.home.lan at HOME.LAN (maybe I'm wrong here?)
Export one principal to z1.keytab
$ klist -k -e test.keytab
Keytab name: FILE: test.keytab
KVNO Principal
---- ----------------------------------------------
----------------------------
    2 z1 at HOME.LAN (aes256-cts-hmac-sha1-96)

the spn does not appear.