current keybase cli cannot login on old accounts!

I have had to wipe my linux machine and have reimported my keys in gpg from a backup.

gpg is happy :
ranyardm@osxreally-af58 ~/Downloads $ gpg --list-keys
/home/ranyardm/.gnupg/pubring.gpg
---------------------------------
pub 2048R/CFAEF3F4 2014-01-10
uid Martyn Ranyard (2014 onwards) <martyn@ranyard.info>
uid keybase.io/imartyn <imartyn@keybase.io>
sub 2048R/5DC2D226 2014-01-10

but keybase refuses to login :

ranyardm@osxreally-af58 ~ $ keybase login
Your keybase username or email address: iMartyn
▶ 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:

4C31 0155 7BA5 83F4 7FF7 9776 AB4A 6048 CFAE F3F4

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

Please don't make me revoke my pgp key and all my proofs :(

Start by reproducing keybase login after importing the account's private PGP key and compare it with gpg --list-keys and the fingerprint shown by the CLI. Trace the login path that searches for the corresponding private key; done means the existing account is recognized without requiring account reset, with regression coverage for this imported-key case.