test causes a Unauthorized exception to be raised, which now correctly is *not*
handled by the publisher, as requested.

**This change needs to be propagated to the Five repository to become
permanent!**

Prevent 'render' function in Expressions.py for being called for basic types (minor speed improvement).  See  http://www.zope.org/Collectors/Zope/1890. 

      - Collector #1879: applied patch by Dieter Maurer to fix a bug in 
        ac_aquire() ignoring the default argument

Collector #1864, #1906: fixed header normalization in appendHeader()

      - Collector #1899: fixed migration issue when using export/import for
        ZCatalog instances

packages than single pieces

  with Python
- remove use of the long-deprecated xmllib module, again using the Expat
  that comes with Python as a replacement

use it

In the interest of keeping myself sane, I've left the "Trunk only
(unreleased)" section alone

and not just when the file is missing. This is a forward port from Zope-2_7-branch.

        ZTUtils.make_query()

      - ZCatalog: refreshCatalog() could not be called safely from a ZEO
        client script

        problems for some .zexp files e.g. Squishdot instances)

use the pushStream/popStream model from the Zope 3 codebase instead of the
interpretWithStream model.  The two are entirely equivalent in context,
but I think the push/pop model offers more flexibility in the long run

rather then runzope to avoid all the hassle with
not detaching and thus mysteriously stopping zopes.