BUG #14485: Error in copy from temp

The following bug has been logged on the website:

Bug reference: 14485
Logged by: Lars Ellebjerg
Email address: lars(at)ellebjerg(dot)net
PostgreSQL version: 9.6.0
Operating system: Windows
Description:

I believe I have experienced an error in copying from a temporary table.

I have a csv-file with a column of ten-digit person registry numbers, some
of which start with zero.
I need to copy them to a column 'cpr' in a table, which also contains an id
serial column.
If I do this by copying them to a temp table with a single text column, and
then inserting them into the permanent table, the initial zero is removed
somewhere between the temp and the permanent table.
If I do the same using a permanent table instead of the temp table, the copy
works fine including the initial zeros.

create temporary table t (x1 text);

copy t (x1)
from 'C:/CPR hjemmesygepleje.csv' delimiter ';' csv;

insert into aeldrepleje.hjemmesygeplejemodtagere (cpr)
select x1 from t;

select * from aeldrepleje.hjemmesygeplejemodtagere;

create table aeldrepleje.hspm (cpr text);

copy aeldrepleje.hspm (cpr)
from 'C:/CPR hjemmesygepleje.csv' delimiter ';' csv;

insert into aeldrepleje.hjemmesygeplejemodtagere (cpr)
select cpr from aeldrepleje.hspm;

select * from aeldrepleje.hjemmesygeplejemodtagere;