Hmmm... I don't know. For me, it works as it should:
Code:
$ ssh root@kindle
[root@kindle root]# mntroot rw
system: I mntroot:def:Making root filesystem writeable
[root@kindle root]# grep ^root /etc/passwd
root:x:0:0:root:/tmp/root:/bin/sh
[root@kindle root]# sed -i -e 's/\/tmp\/root/\/var\/tmp\/root/' /etc/passwd
[root@kindle root]# grep ^root /etc/passwd
root:x:0:0:root:/var/tmp/root:/bin/sh
[root@kindle root]# mntroot ro
system: I mntroot:def:Making root filesystem read-only
[root@kindle root]# echo $HOME
/tmp/root
[root@kindle root]# ^D
Connection to kindle closed.
$ ssh root@kindle
[root@kindle root]# echo $HOME
/var/tmp/root