Comment # 3 on bug 933861 from Dr. Werner Fink

Btw: installing manual pages below /root isn't very common nor reasonable.  It
is the user root who is able to install man pages below /usr/share/man ... for
all other users it might be useful as they can not install manual pages but
extend their MANPATH to an appropiate value.  Neverthless the mandb command nor
the man command should a trojan to be used by others to sniffing below others
users personal MANPATH. Hence the mandb and the man command switch to an other
user.