Use socket.gethostbyaddr to define hostname.

tests/sanity/runtest.sh

@@ -1,14 +1,6 @@
 #!/bin/sh -eux
 
-dnshost="$(hostname)"
-if command -v dig >/dev/null
-then
-    hostip="$(dig +short $(hostname))"
-    if [ -n "${hostip}" ]
-    then
-        dnshost="$(dig +short -x "${hostip}" | sed "s/\(.*\)\./\1/")"
-    fi 
-fi
+dnshost="$(echo "import socket; print(socket.gethostbyaddr('$(hostname)')[0])" | "$(command -v python3)")"
 systemctl unmask gssproxy
 ipa-server-install --hostname=${dnshost} -r EXAMPLE.TEST -n example.test --setup-dns --no-forwarders --allow-zone-overlap -p Secret123 -a Secret123 -U
 echo Secret123 | kinit admin