[pkg-gnupg-maint] Bug#835045: gnupg: cannot edit my key: "secret key parts are not available"

[Julian Gilbey]

Package: gnupg
Version: 1.4.20-6
Severity: important

Hello!

I'm trying to update my gpg key expiry date, but am having
difficulties:

polya:~ $ gpg --edit-key 0x59D03CC92BA0FEAE
Secret key is available.

pub  4096R/0x59D03CC92BA0FEAE  created: 2014-10-29  expires: 2016-10-28  usage: SC
                               trust: ultimate      validity: ultimate
                               sub  4096R/0x14A58BD97483A28B  created: 2014-10-29  expires: 2016-10-28  usage: E
                               sub  4096R/0x695C429316C07BFE  created: 2014-10-29  expires: 2016-10-28  usage: S
                               [ultimate] (1). Julian Gilbey <julian at d-and-j.net>
                               [ultimate] (2)  Julian Gilbey <jdg at debian.org>
                               [ultimate] (3)  Julian Gilbey <J.Gilbey at maths.cam.ac.uk>
                               [ultimate] (4)  Julian Gilbey <jdg18 at cam.ac.uk>

gpg> expire
Changing expiration time for the primary key.
gpg: WARNING: no user ID has been marked as primary.  This command may
              cause a different user ID to become the assumed primary.
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 2y
Key expires at Tue 21 Aug 2018 17:33:49 BST
Is this correct? (y/N) y
gpg: secret key parts are not available
gpg: make_keysig_packet failed: general error

gpg>

And yet I do have my secret key available; "toggle" shows it quite
happily, for example.

So I'm a little stymied.  It might be that gpg2 will fix this issue,
but maybe not.

Any ideas?

Thanks,

   Julian