teaspoon fails on some runners / for some builds

Using the official method for installing node.js fails sometimes:

## Confirming "jessie" is supported...

+ curl -sLf -o /dev/null 'https://deb.nodesource.com/node_6.x/dists/jessie/Release'

## Your distribution, identified as "jessie", is not currently supported, please contact NodeSource at https://github.com/nodesource/distributions/issues if you
think this is incorrect or would like your distribution to be considered for support

(see https://gitlab.com/winniehell/gitlab-ce/builds/3009087 for example)

cc @grzesiek