public key listing fails if ECC subkey uses SHA512

[Nosphky]

Using Gnupg 2.0.22-3ubuntu1.3 (in UbuntuStudio 1404 LTS)

With appearance of gnupg 2 Modern which is now at 2.1.4, increasing numbers of users are creating and using ECC keys or subkeys. Of course 2.0.xx cannot handle these keys but in 2.0.22 if one of the keys in the pubring has a subkey which uses SHA512, then an attempt to list pubkeys with gpg2 -k fails to complete with the following error message :

gpg: Ohhhh jeeee: can't encode a 512 bit MD into a 608 bits frame
Aborted (core dumped)

and returns error code 134

The presence of a single such key in the keyring also prevents enigmail displaying details of some keys.

More details of the discussion are on the user thread of gnupg-users list started on 18 May 2015 under subject heading

"Ohhhh jeeee: can't encode a 512 bit MD into a 608 bits frame"

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Hanno Stock (hefe_bia) (hanno-stock)]

This affects 14.04 LTS. This is fixed in 2.0.23 according to debian bug tracker.

Since this makes gpg2 completely crash when such a key is in the keyring, I guess this should be fixed for the LTS version.