I just tried to add the debian repo for my testing system as per the instructions. I replace 'jessie' in the template with 'testing' but on apt-get update, I get the following error message:

W: Conflicting distribution: http://packages.x2go.org testing InRelease (expected testing but got stretch)

Stretch is the current testing name. Testing seems to be available here, so I don't know what's causing this. Changing the dist name to stretch fixes the issue - however this will require changes to the sources.d file once the dist name changes in the future (not a big deal but still weird).

Just wanted to let you know and would be interested in suggestions.

Best,

Sebastian