Make sh(1) recognize the default $HOME. By default /home
is a symlink; without this change, when you log in, sh(1)
won't realize the current directory (eg '/usr/home/test')
is the same as $HOME ('/home/test').

Reviewed by: jilles
MFC after: 2 weeks
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D18775