sudo is sometimes slow if the hostname has been changed from `pureos` (/etc/nsswitch.conf)

##TL;DR

• if the hostname has been changed to something other than the default pureos it can sometimes take a long time for the sudo password prompt to show up
• put myhostname before dns in /etc/nsswitch.conf in the hosts: line

Spawned from a recent discussion on matrix starting at https://matrix.to/#/!FwbcAdwtvCYkHekZKf:talk.puri.sm/$0lyWbU8NOF2eIUAQ1dnvYsJwAOdujg43MyqgpDOfAns?via=talk.puri.sm&via=matrix.org&via=librem.one

I mitigated this locally by adding my hostname in /etc/hosts, but @sebastian.krzyszkowiak pointed the manpages which read

It is recommended to place "myhostname" after "file" and before "dns". This resolves well-known hostnames like "localhost" and the machine hostnames locally. It is consistent with the behaviour of nss-resolve, and still allows overriding via /etc/hosts.

while I had myhostname after dns, not before.

I've switched the order and will observe if I ever have slow sudo again.