Fix bug intro'ed in #282
Fix bug intro'ed in #282

Don't offer to kex with the Detkey.  There is probably another bug here that's not being tested, in
which there are 3 devices.

Close #289 with better debugging for future bugs.

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client