package PostgreSQL::Test::Cluster::V_11; ## no critic (ProhibitMultiplePackages)
-use parent -norequire, qw(PostgreSQL::Test::Cluster);
+# parent.pm is not present in all perl versions before 5.10.1, so instead
+# do directly what it would do for this:
+# use parent -norequire, qw(PostgreSQL::Test::Cluster);
+push @PostgreSQL::Test::Cluster::V_11::ISA, 'PostgreSQL::Test::Cluster';
# https://www.postgresql.org/docs/11/release-11.html
package PostgreSQL::Test::Cluster::V_10; ## no critic (ProhibitMultiplePackages)
-use parent -norequire, qw(PostgreSQL::Test::Cluster::V_11);
+# use parent -norequire, qw(PostgreSQL::Test::Cluster::V_11);
+push @PostgreSQL::Test::Cluster::V_10::ISA, 'PostgreSQL::Test::Cluster::V_11';
# https://www.postgresql.org/docs/10/release-10.html