I try to setup a build pipeline with a local hydra instance which I set up according to the wiki.
When fetching the flake, I use
git+ssh://git@gitlab.com/somegroup/somerepo
as input.
I have all the keys and permissions set up and it works, hydra fetches the repo and I can see it in the hydra machines /nix/store under …-source.
Problem is, hydra does not fetch the newest commit, always the same old one.
I tried appending the commit hash with
git+ssh://git@gitlab.com/somegroup/somerepo?rev=7a85146c6be5fb9520d873af1c424fb64b338f68
but then it says “Host key verification failed”, which seems weird because hydra can fetch the repo but no individual commits?
I would love to get some guidance on how to proceed 
Update: it works flawlessly when the repo is public.
