copy: update docs for FORCE_NULL and FORCE_NOT_NULL combination

Bruce Momjian <bruce@momjian.us>

Commit: 7ec73783d88a743799b0c262f1235f772497fb1d
Author: Bruce Momjian <bruce@momjian.us>
Date: 2014-04-22T20:06:37Z
Releases: 9.4.0
copy:  update docs for FORCE_NULL and FORCE_NOT_NULL combination

Also update regression tests

Patch by Michael Paquier

Files