setting the timezone parameter with space cause diff result

steps ro reproduce:
postgres=# set timezone='+04:00';
SET
postgres=# select now();
              now              
-------------------------------
 2021-06-08 04:14:26.994218-04
(1 row)


/* timezone string with space */
postgres=# set timezone=' +04:00 ';
SET
postgres=# select now();
              now              
-------------------------------
 2021-06-08 05:14:36.486693-03
(1 row)


postgres=#