Comment 18 for bug 1881196

Fix verified for focal.

$ lsb_release -rd
Description: Ubuntu 20.04 LTS
Release: 20.04

Did a fresh, vanilla install of focal.
installed postfix, ssl-cert - accepted all defaults
  # sudo apt install postfix ssl-cert
Tested to ensure that fault existed
  # postfix tls deploy-server-cert /etc/ssl/certs/ssl-cert-snakeoil.pem /etc/ssl/private/ssl-cert-snakeoil.key

applied patch from http://launchpadlibrarian.net/485381331/postfix_3.4.10-1ubuntu1_3.4.13-0ubuntu1.diff.gz
  # patch -d/ --ignore-whitespace -p0 /usr/lib/postfix/sbin/postfix-tls-script <<'EOF'
diff -Nru postfix-3.4.10/conf/postfix-tls-script postfix-3.4.13/conf/postfix-tls-script
--- postfix-3.4.10/conf/postfix-tls-script 2017-02-19 01:58:20.000000000 +0000
+++ postfix-3.4.13/conf/postfix-tls-script 2020-05-30 14:37:04.000000000 +0000
@@ -777,7 +777,7 @@
 deploy_server_cert() {
     certfile=$1; shift
     keyfile=$1; shift
- deploy=$1; shift
+ case $# in 0) deploy=;; *) deploy=$1; shift;; esac

     # Sets key_algo, key_param and cert_param
     check_key "$keyfile" || return 1
EOF

Verified fix. - focal.

--

Did a fresh, vanilla install of focal.
installed ssl-cert
  $ sudo apt install ssl-cert
Installed postfix/focal-proposed from postfix_3.4.13-0ubuntu1_amd64.deb
  $ sudo dpkg -i postfix_3.4.13-0ubuntu1_amd64.deb
Tested script
  $ postfix tls deploy-server-cert /etc/ssl/certs/ssl-cert-snakeoil.pem /etc/ssl/private/ssl-cert-snakeoil.key

Verified fix - focal

--

Did a fresh , vanilla install of bionic
installed postfix, ssl-cert - accepted all defaults
  # sudo apt install postfix ssl-cert
Tested to ensure that fault existed
  # postfix tls deploy-server-cert /etc/ssl/certs/ssl-cert-snakeoil.pem /etc/ssl/private/ssl-cert-snakeoil.key

applied patch from http://launchpadlibrarian.net/485381331/postfix_3.4.10-1ubuntu1_3.4.13-0ubuntu1.diff.gz
  # patch -d/ --ignore-whitespace -p0 /usr/lib/postfix/sbin/postfix-tls-script <<'EOF'
diff -Nru postfix-3.4.10/conf/postfix-tls-script postfix-3.4.13/conf/postfix-tls-script
--- postfix-3.4.10/conf/postfix-tls-script 2017-02-19 01:58:20.000000000 +0000
+++ postfix-3.4.13/conf/postfix-tls-script 2020-05-30 14:37:04.000000000 +0000
@@ -777,7 +777,7 @@
 deploy_server_cert() {
     certfile=$1; shift
     keyfile=$1; shift
- deploy=$1; shift
+ case $# in 0) deploy=;; *) deploy=$1; shift;; esac

     # Sets key_algo, key_param and cert_param
     check_key "$keyfile" || return 1
EOF

Verified fix - Bionic