GitLab does not recognize new PGP subkeys
Problem to solve
Your documentation helpfully explains how to sign commits with your PGP key, which has worked for me in the past. However, recently I started using PGP subkeys that didn't exist at the time I uploaded my public key.
To get GitLab to recognize my new subkey, I tried to add my public key again, upon which I got an error saying this key already exists. The problem now is that it did exist, but I also added new subkeys to it. I would expect GitLab to recognize this. The only way to get GitLab to recognize my new subkey was to remove my public key and add it again. After I added my public key again, GitLab recognized my new subkeys.
Devon, Sasha and anyone else who wants to have verified commits with new subkeys.
The benefit here is taking away unexpected behavior. Nowhere does it say that removing and adding your public key again will work. But to get to this point even, you have to guess re-adding it will even work, because all you get it an error saying this key already exists (which it does, but now there's new subkeys attached to it). This is confusing UX.
I'm not sure if it is technically feasible to recognize that there are new subkeys attached to a public key, but if it is I would propose that GitLab recognizes this and updates the key. Even if this is technically possible, a small note to the documentation to inform users of this possibility is helpful.
If it is not technically possible to do this, I would expect a new paragraph to be added to the documentation to inform users of what to do (i.e., remove and add the same public key) when they want to add a new subkey.
What does success look like, and how can we measure that?
Success will either be an implementation that recognizes new subkeys, or an update to the documentation.