Suggestions for debugging "gnutls_handshake() failed"?

[Martin Packman]

A number of users are experiencing a gnutls related issue from pycurl
when running the launchpad-login command, that does not seem to have
been fixed by the other recent curl change:

<https://bugs.launchpad.net/bzr/+bug/851834>

Does anyone have any ideas on useful debugging that we could suggest
those affected to try? Being able to retarget the bug to the right
package or narrow down the what the trigger is would be useful. I had
a feeling there was some extra lore in the list archives about this
issue, but can't find anything relevant.

Martin