how to verify the trust path to a gpg key?

I want to check whether the gpg key used by Julien Danjou for his emacs snapshot repository can be trusted. There are many trust paths from my key to Juliens key. But I can't believe that there shouldn't be any gpg command which just answers this simple question from my local keyring. Or is there?

Apparently I'm not the only one having this problem.

You're right to be concerned; that Julien Danjou guy is slippery. (Kidding!)

I believe you're looking for this command:

gpg --list-keys --list-options show-uid-validity 8B78A5C2

You can use pathfinder sites like Henk P. Penning's pathfinder, although they need you to push the keys to specific keyservers.

There's also the sigtrace tool, but that one requires that you import all the intermediate keys in your keyring, which can generate quite a lot of noise.