This question occured in the comments of "How do I display the usage flags for my encryption keys in a less hackish way?", and seems worth being answered in a Q&A form as the answer is not actually obvious.
To view Torvald's OpenPGP key 449FA3AB, I use
gpg2 --list-keys 449FA3AB, which outputs
$ gpg2 --list-keys 449FA3AB pub 1024D/449FA3AB 1999-10-05 [expired: 2001-10-04] uid [ expired] Linus Torvalds <email@example.com>
Usually, this command also lists subkeys, but no subkeys are printed for Torvald's key. Yet, when requesting batch output, there is one included.
$ gpg2 --with-colons --list-keys 449FA3AB tru::1:1414619239:1414879758:3:1:5 pub:e:1024:17:956EB7BF449FA3AB:939086351:1002158351::-:::sca: uid:e::::939086351::81A3799583B9B1B391E4C428112F302FF2ADF462::Linus Torvalds <firstname.lastname@example.org>: sub:e:2048:16:71CE8207BFF491C5:939086545:1002158545:::::e:
Seems like this Torvalds-key has some special feature that hides the sub-key. What happened here?