/usr/share/postgresql/10/extension/ is in postgresql-10-unit 5.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/postgresql/10/extension/unit--1--2.sql
/usr/share/postgresql/10/extension/unit--1.sql
/usr/share/postgresql/10/extension/unit--2--3.sql
/usr/share/postgresql/10/extension/unit--2.sql
/usr/share/postgresql/10/extension/unit--3--4.sql
/usr/share/postgresql/10/extension/unit--3.sql
/usr/share/postgresql/10/extension/unit--4--5.sql
/usr/share/postgresql/10/extension/unit--4.sql
/usr/share/postgresql/10/extension/unit--5.sql
/usr/share/postgresql/10/extension/unit.control
/usr/share/postgresql/10/extension/unit_prefixes.data
/usr/share/postgresql/10/extension/unit_units.data