Can't re-prove my web site

```
$ keybase prove --force -o out web mat.cc

Une phrase de passe est nécessaire pour déverrouiller la clef secrète de
l'utilisateur : « Mathieu Arnold  »
clef RSA de 4096 bits, identifiant 3A4516F35183CE48, créée le 2013-09-23

error: A live proof for http://mat.cc already exists (error #230)
$ keybase revoke-proof -f web http://mat.cc/
error: No proof found for service 'generic_web_site'
```

stuck seems to be the word :)

Start by reproducing the `keybase prove --force -o out web mat.cc` and `keybase revoke-proof -f web http://mat.cc/` commands from the issue. Trace how the CLI handles the existing live proof and the `generic_web_site` service, then verify that an existing proof can be re-proved or revoked without contradictory errors.

Written by the indexing model from the issue text.