If all that fails, you can download and import the key manually:
curl 'http://pgp.surfnet.nl:11371/pks/lookup?op=get&search=0x38DBBDC86092693E' > gregkh.key
gpg --import gregkh.key
Release top of distribution archive description and integrity information
Release.gpg top of distribution signature file for the "Release" file signed with the archive key