Installing QGIS3 in Debian from upstream repo

[Andrew Harvey <andrew.harvey4@gmail.com>]

Since QGIS in Debian won't be updated to version 3 until the QGIS 3.4
LTR event which looks like will be in Feb 2018
https://www.qgis.org/en/site/getinvolved/development/roadmap.html,
I've been looking for the most debianish way to install the latest
QGIS, and it seems to be via the upstream QGIS Debian repo at
https://qgis.org/en/site/forusers/alldownloads.html#debian-ubuntu

Since they prefix their versions with 1, I needed to do this to install it:

sudo apt-get install qgis=1:3.2.3+99unstable
python-qgis=1:3.2.3+99unstable qgis-providers=1:3.2.3+99unstable
qgis-common=1:3.2.3+99unstable python-qgis-common=1:3.2.3+99unstable
qgis-providers-common=1:3.2.3+99unstable

Hope this helps anyone else wanting QGIS 3 in Debian.

Is there a better way to do this?