Incompatible secret key format between 2.4.4 and 2.2.27?

[mlist_e9e869bc at manycementmutable.anonaddy.com]

On 13/02/2024 09:57, Werner Koch 'wk at gnupg.org' wrote:
> Can you please try to import that key (with the v5 key signature) using
> a current 2.2. version (2.2.42)?  Or you can send me the public key by
> private mail so that I can check what's going on.
>
>
> Salam-Shalom,
>
>     Werner
>
I couldn't find a distro with 2.2.42 so I have to compile it myself. I'm 
using Docker with ubuntu:latest.

In conclusion, the import failed.

```
$ gpg --version
gpg (GnuPG) 2.2.42
libgcrypt 1.9.4
Copyright (C) 2023 g10 Code GmbH
License GNU GPL-3.0-or-later <https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Home: /root/.gnupg
Supported algorithms:
Pubkey: RSA, ELG, DSA, ECDH, ECDSA, EDDSA
Cipher: IDEA, 3DES, CAST5, BLOWFISH, AES, AES192, AES256, TWOFISH,
         CAMELLIA128, CAMELLIA192, CAMELLIA256
Hash: SHA1, RIPEMD160, SHA256, SHA384, SHA512, SHA224
Compression: Uncompressed

$ gpg --import PUBLIC_v5_certify.asc
gpg: packet(2) with unknown version 5
gpg: read_block: read error: Invalid packet
gpg: import from 'PUBLIC_v5_certify.asc' failed: Invalid keyring
gpg: Total number processed: 0
```

Is wk at gnupg.org the private email I can send the public key to you? 
I'm willing to send you a copy to examine but not publicly as that's 
(now I remember) a result of a dumb experiment.

Regards,
Hartman