MANPATH resets output paper setting

[Jan Stary]

This is current/amd64 on a PC.

It seems that if MANPATH is set (to something nonempty),
the settings in /etc/man.conf get ignored:
        $ cat /etc/man.conf
        output paper a4

        $ man -Tps true | grep PageSize 
        %%BeginFeature: *PageSize Letter
        <</PageSize [612 790]>>setpagedevice

        $ env | grep MAN
        MANPATH=/home/hans/man:/usr/local/man:/usr/share/man:/usr/X11R6/man

        $ export MANPATH=
        $ man -Tps true | grep Size 
        %%BeginFeature: *PageSize A4
        <</PageSize [595 841]>>setpagedevice

Jan