Repeatable builds using pkgbase

While working on build scripts for FreeBSD container images, I wanted to
get to the point where my builds are repeatable, i.e. if I create two
images with the same set of packages installed in the same order, they
should be identical.

The main stumbling block is timestamps. I can force all the file timestamps
to a fixed value with buildah using the '--timestamp' argument to either
'buildah commit' or 'buildah build' but even then, the two images have
different hashes. Looking deeper, the difference is in
/var/db/pkg/local.sqlite. If I compare SQL dumps of the databases from each
image, I can see a timestamp embedded in the sqlite file:

diff dump1 dump2


4c4
< INSERT INTO packages
VALUES(1,'base','FreeBSD-zoneinfo','13.2p2','zoneinfo package','zoneinfo
package',NULL,NULL,'FreeBSD:13:amd64','re@FreeBSD.org','
https://www.FreeBSD.org
','/',731014,0,0,1,1692446701,'2$2$c9w95oqai9bwhny1k4pcg8mji77xgk43zjxxb69j1duzq5jao18wak4deer85epmfpc8ngyysyt9wu74pg7sczkqc3ekyawkfgwzi8d',NULL,NULL,0);
---
> INSERT INTO packages
VALUES(1,'base','FreeBSD-zoneinfo','13.2p2','zoneinfo package','zoneinfo
package',NULL,NULL,'FreeBSD:13:amd64','re@FreeBSD.org','
https://www.FreeBSD.org
','/',731014,0,0,1,1692622924,'2$2$c9w95oqai9bwhny1k4pcg8mji77xgk43zjxxb69j1duzq5jao18wak4deer85epmfpc8ngyysyt9wu74pg7sczkqc3ekyawkfgwzi8d',NULL,NULL,0);


Looking at the pkg source, I can see that the prepared statement for
inserting into the packages table explicitly uses NOW() for this column.
Would it be reasonable to allow changing this, e.g. by adding a command
line argument to pkg to override the default? I haven't tried this to see
if that makes the two databases identical - if not, I guess I'll just
remove pkg metadata altogether.