Comment 22 for bug 1641615

Build worked but my assumption of "other" changes became true, yet in a different way than I thought.
See this thread on libvirt which made me aware of gnutls actually taking back some of the changes:
https://www.redhat.com/archives/libvir-list/2016-November/msg00815.html

So it turns out that was identified an unallowed abi change in gnutls - not released.
commit 70bf8475bb0ab178fe36ee4c601a6cfec8e70a3f
Author: Nikos Mavrogiannopoulos <email address hidden>
Date: Fri Nov 11 16:20:01 2016 +0100

    Introduced new functions to allow multiple DN parsing modes

    The old DN parsing functions are changed to return the original
    non-fully compliant with RFC4514 string format, while the new
    ones return the compliant string by default. This allows applications
    which relied on the previous format to continue functioning without
    changes.

So in turn we need to update gnutls and then libvirt (back to where we started).

Also we have broken nova-compute dep8 tests (https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-zesty/zesty/i386/n/nova/20161116_153913_48850@/log.gz) on the recent uploads, which might (or not) be related to this overall thing - only willing to spend more time once the gnutls/libvirt changes are back to where they should be.