~/.sudo_as_admin_successful causes NFS hang

Binary package hint: sudo

Accessing the file ~/.sudo_as_admin_successful can cause sudo to fail
when an NFS server is down or unreachable.

Before running the requested command, sudo (1.7.2p1-1ubuntu5.2)
touches the file .sudo_as_admin_successful in the user's home
directory.

In the failure scenario, your home directory is an NFS mount, the
network has gone down, and you need root access to fix it. Alas, your
sudo command hangs, because it is trying to access a network file, and
thus you cannot fix the network.

Putting this flag file in /var/lib/sudo/$LOGNAME-as-admin-successful
would be safer, because /var/lib is more likely to be on a local
file-system.

Please consider whether this Ubuntu addition of touching a file is
justified at all. It adds to code complexity. (There has already
been at least one bug filed (and fixed) against it.) It adds to the
Ubuntu patch burden. And it provides only the modest benefit of
allowing /etc/bash.bashrc to inform some people when they log in that
they can use sudo to be root.

We sometimes need to use sudo in emergencies, when things aren't
working well. Thus, sudo should be simple and streamlined, so we can
count on it working when other things are broken. Please, be very
reluctant to add new code to sudo.