During the Red Hat 3scale API Management 2.X On-premises upgrade, the "Import the database backup" step fails with several "already exists" SQL errors

Issue

When restoring the backup of PostgreSQL, few of errors were observed during restore process:

# zcat zync-database-backup-for-2.5.gz | oc rsh $(oc get pods -l 'deploymentConfig=zync-database' -o json | jq '.items[0].metadata.name' -r) bash -c 'psql -d postgres -f -'
SET
SET
SET
psql:<stdin>:14: ERROR:  role "postgres" already exists

...

psql:<stdin>:1539: ERROR:  constraint "fk_rails_c99dfff855" for relation "services" already exists
psql:<stdin>:1547: ERROR:  constraint "fk_rails_cbcddd5826" for relation "applications" already exists
psql:<stdin>:1555: ERROR:  constraint "fk_rails_cd54ced205" for relation "integrations" already exists
psql:<stdin>:1563: ERROR:  constraint "fk_rails_d329ca1b17" for relation "integrations" already exists
REVOKE
REVOKE
GRANT
GRANT