/usr/share/postgresql/9.6/extension/debversion.control is in postgresql-9.6-debversion 1.0.8-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | # debversion extension
comment = 'A Debian version number data type'
default_version = '1.0.8'
module_pathname = '$libdir/debversion'
relocatable = true
|