Drop database entries only if exists

Override pg_restore pass if necessary.

PROD-34409

Change-Id: I41d163e45853586fcfdb57fc4136868d717203f6
diff --git a/maas/files/restore.sh b/maas/files/restore.sh
index ef187be..2f7f288 100644
--- a/maas/files/restore.sh
+++ b/maas/files/restore.sh
@@ -1,6 +1,7 @@
 {%- from "maas/map.jinja" import region with context %}
 
 {%- set backup_dir = pillar.get('backupninja', {}).get('client', {}).get('target', {}).get("home_dir", "/srv/backupninja") -%}
+{%- set pg_restore = pillar.get('backupninja', {}).get('client', {}).get('extra_params', {}).get("PGSQLRESTORE", "pg_restore") -%}
 {%- set database = region.get("database", {}) -%}
 
 export PGHOST={{ database.get("host", "localhost") }}
@@ -29,7 +30,7 @@
 sudo systemctl stop maas-rackd.service
 sudo systemctl stop maas-regiond.service
 
-pg_restore {{ target }}/{{ db_name }}.pg_dump --dbname={{ db_name }} --no-password -c
+{{ pg_restore }} {{ target }}/{{ db_name }}.pg_dump --dbname={{ db_name }} --no-password -c --if-exists
 
 # Restore file permissions
 if [ "$(which setfacl)" != "" ]; then