install: Ad production support for Zulip on Ubuntu Focal.

Install script now runs on Focal.  Python 2 is now installed via the
`python2` package in Focal.

puppet/zulip/manifests/base.pp

@@ -15,6 +15,7 @@ class zulip::base {
         '15.10' => 'wily',
         '16.04' => 'xenial',
         '18.04' => 'bionic',
+        '20.04' => 'focal',
       }
       $base_packages = [
         # Accurate time is essential
@@ -67,6 +68,7 @@ class zulip::base {
     'xenial'  => '9.5',
     'bionic'  => '10',
     'CentOS7' => '10',
+    'focal'   => '12',
   })
 
   $normal_queues = [

scripts/lib/install

@@ -105,7 +105,7 @@ if [ -f /etc/os-release ]; then
 fi
 
 case "$os_id$os_version_id" in
-    ubuntu16.04|ubuntu18.04|debian9|debian10) ;;
+    ubuntu16.04|ubuntu18.04|debian9|debian10|ubuntu20.04) ;;
     *)
         set +x
         cat <<EOF
@@ -203,9 +203,15 @@ fi
 
 case " $os_id $os_id_like " in
     *' debian '*)
+        if [ "$os_id" = ubuntu ] && [ "$os_version_id" = 20.04 ]; then
+            PYTHON2="python2"
+        else
+            PYTHON2="python"
+        fi
+
         if ! apt-get install -y \
             puppet git curl wget jq \
-            python python3 python-six python3-six crudini \
+            "$PYTHON2" python3 python-six python3-six crudini \
             "${ADDITIONAL_PACKAGES[@]}"; then
             set +x
             echo -e '\033[0;31m' >&2