Bad signature uploaded: We don't have a key for the requested PGP ops

I signed my uploaded public key as per the given command (adjusted for gpg2)

```
$ echo '{"body":{"key":{"fingerprint":"42725dc053624f593cedccd7904f63306ae405c8","host":"keybase.io","key_id":"904f63306ae405c8","uid":"1e6100566ef04c0fc7ca9420a1327a00","username":"ilia"},"type":"web_service_binding","version":1},"ctime":1394075926,"expire_in":157680000,"prev":null,"seqno":1,"tag":"signature"}' | gpg2 -u '904F63306AE405C8' -a --sign
```

After uploading the signed message to keybase.io, I am getting the following.


Start by reproducing the signed-message upload with the provided gpg2 command and compare the resulting error with the linked screenshot. No repository file or test is named in the issue, so trace the upload handling for this signature format. Done means the valid signed public-key message is accepted without the reported missing-key error.

Written by the indexing model from the issue text.