GnuPG 2.1 homedir looks different, so just create it on the fly by
importing needed private and public keys and ownertrust.
This solves an issue with gnupg 2.1 running interactive pinentry
when old secret key is present.
Signed-off-by: Christian Hesse <mail@eworm.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
