gpg: error getting the KEK: Unsupported certificate

[Abel Luck]

I'm getting this error on gpg2 master whenever I try to import a secret
key exported from 1.4.13

$ gpg-agent  -v --daemon
gpg-agent[12554]: listening on socket '/home/user/.gnupg/S.gpg-agent'
GPG_AGENT_INFO=/home/user/.gnupg/S.gpg-agent:12555:1; export GPG_AGENT_INFO;
gpg-agent[12555]: gpg-agent (GnuPG) 2.1.0-beta108 started

$ gpg2 --import secret-keys.gpg
gpg: NOTE: THIS IS A DEVELOPMENT VERSION!
gpg: It is only intended for test purposes and should NOT be
gpg: used in a production environment or with production keys!
gpg: key 51EF9A28: "Test Key (pin: 1234)" not changed
gpg: error getting the KEK: Unsupported certificate
gpg: Total number processed: 1
gpg:              unchanged: 1
gpg:       secret keys read: 1

I've tried going back to 36ba7845995dd3caf8faeec3e09b3ffb879fc29b but
I'm getting the same results. I figure if I go back any farther I'll
start running into compatibility issues with the other gnupg repos
(e.g., libgpg-error)

I encountered this while playing with the new pinentry modes for the
Android port.

~abel