utility cannot find the corresponding private key on this machine

OS: Ubuntu 16.04 LTS
keybase version 1.0.17-20161024194756+4dcf351

Getting this after `keybase login`

```
▶ ERROR Sorry, your account is already established with a PGP public key, but this
utility cannot find the corresponding private key on this machine.
This is the fingerprint of the PGP key in your account:

`#### #### #### #### #### #### #### #### 9FD7 C2C1`

You need to prove you're you. We suggest one of the following:

- put one of the PGP private keys listed above on this machine and try again
- reset your account and start fresh: https://keybase.io/#account-reset

```

but
`gpg --list-secret-keys` yields

```
sec 4096R/9FD7C2C1 2015-10-08 [expires: 2025-10-05]
uid keybase.io/jamysz
```

How do I point keybase to my keys?

Reproduce `keybase login` on Ubuntu 16.04 with keybase version 1.0.17 and compare its behavior with `gpg --list-secret-keys`, using the reported fingerprint as the reference. Done means the utility recognizes the corresponding private key or clearly reports why it cannot.

Written by the indexing model from the issue text.