[GNOME] Repository is not signed
Issue generated from Tuleap's migration script. Originally submitted by: Óvári (ovari)
OS: Linux Mint 18.3 Cinnamon 64-bit
In the terminal:
$ sudo apt-get update && sudo apt-get install ring
W: GPG error: https://dl.ring.cx/ring-nightly/ubuntu\_16.04 ring InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 64CD5...
W: The repository 'https://dl.ring.cx/ring-nightly/ubuntu\_16.04 ring InRelease' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
Removed, please advise if you need the complete key: 64CD5...