Exporting/ importing changes expiration date of subkeys...

[gnupgpacker]

Hello,
and thanks for reply!

> the "classic" version of GnuPG (the 1.4.x series) not only does not
> ... 
> If you upgrade to the modern version of GnuPG on your windows machine,
> and then try to re-import, i think you'll find the merge issue resolved.

GnuPG 1.4.23 is part of GnuPG-Pack with old but convincing GPGrelay
included, which needs older version 1.4x.
http://www.rose-indorf.de/gnupgpack/ 

Exporting (older) RSA keys should be independent from GnuPG version 1.4x or
2.2x, isn't it?

Importing those keys are working faultless with:
Flipdog CryptoPlugin/ Android-8.1:
https://i.imgur.com/TmR3oiz.png 
and 
OpenKeychain/ Android-8.1 too:
https://i.imgur.com/vYa1pUl.png 
Expiration dates of key and 3 subkeys are correct set to 31.12.2019!

Only importing with R2mail2/ Android-8.1 causes described expiration error.
In my opinion it depends on key structure (1 main key, 3 subkeys for
S/A/E)!?
If using a 'normal' key with 1 main key S/C/A and 1 subkey for E, importing
to R2mail2 works, even if expiration date has been enhanced.

Any hint how to bypass this issue? 
Thx + regards.