pi@raspberrypi:~ $ sudo apt-get update
Hit:1 http://debian.koha-community.org/koha stable InRelease
Hit:2 http://archive.raspberrypi.org/debian stretch InRelease
Hit:3 http://raspbian.raspberrypi.org/raspbian stretch InRelease
Reading package lists... Done
pi@raspberrypi:~ $ sudo apt-get koha-common mariadb-server
E: Invalid operation koha-common
pi@raspberrypi:~ $ sudo apt-get install koha-common mariadb-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 koha-common : Depends: libnet-oauth2-authorizationserver-perl but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
pi@raspberrypi:~ $