I have not solved the problem, but I have determined the cause, and
this is not the right forum.
Apparently the Libpq that psql is using was compiled from source an
was libpq.so.5.1, while DBD::Pg 1.77 was compiled against the
Ubuntu-supplie libpq.so.4.1. After doing reasearch it looks like
there may be issues with the Ubuntu-shipped library.
No need to worry about this.