Merge 'dont-update-metadata' fix from 2.6 branch.  When the caller specifies that only a particular set of indexes should be updated, don't update the object metadata unconditionally.

This unifies the convention in templates, scripts, and Zope 3.

'default' are still fully escaped.

without an emergency user (the original test was failing; now we're
more thorough)

caught by pychecker

In the past, if you ran an appserver as ZEO client with a persistent
cache, the startup logic prevented products from being loaded.  This
was a hack that got baked in via the weird interaction between the
FORCE_PRODUCT_LOAD and ZEO_CLIENT environment variables and was carried
over into Zope 2.7 by inertia.  Now they have nothing to do with each other
and can be specified independently.

dynamic attribute values as well as static values.

     - Collector #851: Traversable.py: A bare try..except shadowed
       conflict errors

     - Collector #1058: Several fixes for PropertySheets when used
       outside ZClasses

       outside ZClasses

       terms into unrestricted search.

Dont attempt to get a message from the FTPResponse object and show it in the message response (it could be HTML and could contain newlines).

       so that they now log exceptions that occur.

-fix for 1 attribute only

This code looks for the __error_log__ attribute in order to report an
error.  If it finds no such attribute, it reports the error in a
different way.  Unfortunately, the alternative branch was reporting
the exception that just happened to occur most recently, which is
irrelevant; it needs to report the error that was passed to it.
Fixed.

Please make all future changes on the Zope-2_7-branch instead.

imports Python.h.