keybase id/track/etc. for one particular user: error: Can't find a key for 03d65022348f1c0d: We don't have a key for the requested PGP ops (flags = 2)

When I run "keybase id arthurfabre" (a person I know in real life, he's watching me as I type this), I get:

```
error: Can't find a key for 03d65022348f1c0d: We don't have a key for the requested PGP ops (flags = 2)
```

Another user has tried this and they get the same. I have previously tracked arthur, this other user has not. The only person for whom is doesn't happen is Arthur himself.

This is a bit weird. He DID change his key's capabilities recently (which is not something that gpg supports by default), which might have caused it, but I don't know.

I can still send him encrypted email and everything so his keys are probably working, so yeah, weird.

Start by reproducing `keybase id arthurfabre` and compare the reported key-capability error with the successful encrypted-email behavior described here. Done means the identity lookup completes without the missing-key error while encryption continues to work.

Written by the indexing model from the issue text.