That "nss-myhostname" message & correcting the /etc/hosts file

[Adam Funk]

On 2015-04-15, Tom H wrote:

> Ubuntu sets up "/etc/hosts" in this way:
>
><begin>
> 127.0.0.1 localhost ...
> 127.0.1.1 <hostname>.<domainname> >hostname
></end>

You're right --- I'm so used to seeing 127.0.0.1 that I misread the
second line of my file!

> (not "127.0.1.1 <hostname>.<domainname> <hostname>") but hostnamectl
> doesn't update "/etc/hosts" when you use it to change the hostname,
> because nss-myhostname (libnss-myhostname in Ubuntu) is part of
> systemd upstream; hence the warning.
>
> Steve L's objection no longer applies (and might not have applied when
> he posted to Launchpad) because Ubuntu patches libnss-myhostname to
> use 127.0.1.1 rather than 127.0.0.2 as set up upstream.
>
> I use libnss-myhostname on the Ubuntu systems that I manage. Here's
> the output from my laptop running 15.04:

OK, so I should install it now.  Thanks.  

Any idea why the default Ubuntu install is set up to cause this
warning?