**my setup**
i have an offline .gnupg/ directory where all encryption keys are available.
i use an OpenPGP card together with my daily .gnupg/ where the private part of the encryption subkey is only available on the card.
**situation**
the encryption subkey expired, so i generated a new encryption subkey in my offline .gnupg/. then i imported it into my online .gnupg/ and from there moved it onto my card. all worked well until this point.
then i wanted to copy the secret subkey of the previous (now expired) encryption key, so that i can continue reading old emails encrypted to my previous subkey.
**the bug**
i cannot import the subkey into my online .gnupg/
even if i first delete the previous subkey, and then import it from my offline .gnupg/, it still remains marked as a stub of a card key (as opposed to be a full private subkey that i can use to decrypt old emails).
i double checked that the subkey was exported from the offline .gnupg/ where the private key is available.
**log (trimmed)**
```
$ gpg --version
gpg (GnuPG) 2.1.18
libgcrypt 1.7.6-beta
$ gpg --homedir ./full-key/ --edit-key [master-key-id]
ssb rsa4096/[subkey-id]
created: 2015-08-27 expired: 2017-08-26 usage: E
$ gpg --homedir ./full-key/ --export-secret-subkeys [subkey-id] >/run/shm/secret-subkey.gpg
$ gpg --edit-key [master-key-id]
ssb rsa4096/[subkey-id]
created: 2015-08-27 expired: 2017-08-26 usage: E
card-no: [card-id]
gpg> key 8
ssb* rsa4096/[subkey-id]
created: 2015-08-27 expired: 2017-08-26 usage: E
card-no: [card-id]
gpg> delkey
Do you really want to delete this key? (y/N) y
[gone]
gpg> save
$ gpg --import /run/shm/secret-subkey.gpg
gpg: key [master-key-id]: "[user-id]" 1 new signature
gpg: key [master-key-id]: "[user-id]" 1 new subkey
gpg: To migrate 'secring.gpg', with each smartcard, run: gpg --card-status
gpg: key [master-key-id]: secret key imported
gpg: Total number processed: 1
gpg: new subkeys: 1
gpg: new signatures: 1
gpg: secret keys read: 1
gpg: secret keys unchanged: 1
$ gpg --edit-key [master-key-id]
ssb rsa4096/[subkey-id]
created: 2015-08-27 expired: 2017-08-26 usage: E
card-no: [card-id] <------- my problem
```