GNOME Bugzilla – Bug 746816
gnome-keyring's ssh agent does not support RSA-CERT and DSA-CERT keys
Last modified: 2018-03-09 15:37:53 UTC
Work is switching to requiring RSA-CERT keys, gnome-keyring doesn't want to load those.
gnome-keyring should just wrap stock ssh-agent to solve this problem: https://bugzilla.gnome.org/show_bug.cgi?id=775981