/usr/share/postgresql/10/extension/debversion.control is in postgresql-10-debversion 1.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | comment = 'Debian version number data type'
default_version = '1.1'
module_pathname = '$libdir/debversion'
relocatable = true
|