Clarify that pre-method 9 footers contains signatures

When parsing moria1's two votes from 2011-01-15 17:00:00 and from 18:00:00, Stem complains that the key certificate in the 18:00:00 vote doesn't end with a 'dir-key-certification' line:

ParsingFailure: Key certificates must end with a 'dir-key-certification' line:
dir-key-certificate-version 3
fingerprint D586D18309DED4CD6D57C18FDB97EFA96D330566
dir-key-published 2011-01-09 19:54:35
dir-key-expires 2012-01-09 19:54:35
dir-identity-key
-----BEGIN RSA PUBLIC KEY-----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-----END RSA PUBLIC KEY-----
dir-signing-key
-----BEGIN RSA PUBLIC KEY-----
MIGJAoGBAJgW/y9OWLvXnYr9KAqtnEIz+UEXrwcKgCiQLl45s7EftnHLVUqjCJg5
aBKotu+kqo6W2ZKjRP+dkLi8OcjgD1vj/Q0A+248u6pIYAEUg/xJ1T8wBOwzlOuA
yiy082mSAgjhX0yPrl9LDVbnlrUuCOxS2iGjYlotikQw35I5OKdTAgMBAAE=
-----END RSA PUBLIC KEY-----
dir-key-crosscert
-----BEGIN ID SIGNATURE-----
L9b0s7SUZqjDtkZJcegVA9OecbdBljfWlQE3JOsf3QOe5c5G8eGZtOeO1IgEcK2j
pOATJyGVgDigHV9yPEbBNah1q1g56Tdk5XQLr2qFhf6ffZtpFoJkZFo7IWWGIGL+
V0XPcT9ux1el+53Cakik8AN5AApneBm2kA2BEsgswUI=
-----END ID SIGNATURE-----
dir-key-certification
-----BEGIN SIGNATURE-----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-----END SIGNATURE-----
directory-signature D586D18309DED4CD6D57C18FDB97EFA96D330566 2B83C6BE3EC75E91270444DAE41F80A9EFD38912
-----BEGIN SIGNATURE-----
dG60Bz/UV5isZRwowblGYjZhSpeKDo/t5T6UnnPPpZSFdFiVB2LZczfNB7ydt0s6
Jo8IaR4wAqThtWtHSwoVR3pPmLnlDNruNvSjSGfoCpb9jhnDEh0C399A1rimGRNF
6wVp2TJsNQCk91h/nfAtl9g3pepcefpDTWO0Ckr1Phg=
-----END SIGNATURE-----

Parsing the 17:00:00 vote works fine. I don't see what's different between these two votes, and why Stem wouldn't like the 18:00:00 vote. There are other votes that Stem doesn't like for the same reason. I temporarily uploaded the two votes here for easier analysis, though they're also contained in the metrics tarballs.