[ZCM] [ZC] 2119/ 1 Request "Requiring 'site.zcml' breaks BBB"

[Collector: Zope Bugs, Features, and Patches ...]

Issue #2119 Update (Request) "Requiring 'site.zcml' breaks BBB"
 Status Pending, Zope/bug medium
To followup, visit:
  http://www.zope.org/Collectors/Zope/2119

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= Request - Entry #1 by tseaver on May 30, 2006 4:04 pm

A last-minute change[1] before the 2.10 beta release removed the
fallback mechanism im Five which used a default version of 'site.zcml'
withing the Five product itself.

The fatal error message added in this change says:

  site.zcml is now required to live at '<$INSTANCE_HOME/etc>',
  for sites upgraded from Zope 2.9 please copy site.zcml from your
  installed Zope's skel/etc directory

This is not appropriate BBB behavior.  Correct behavior would
be to attempt to load 'site.zcml' first from '$INSTANCE_HOME/etc',
then to fall back to loading the one in '$ZOPE_HOME/skel' (or
to revert the change which removed the fallback from the Five
product, and load from there instead).

We *cannot* break a site upgrading between stable releases of
Zope merely for our own future convenience.

[1] http://svn.zope.org/Products.Five/trunk/zcml.py?rev=65450&r1=68373&r2=65450

I would argue that this change should be reverted, and perhaps
replaced with one which preserves appropriate backward
compatibilit.  I am not convinced that the change itself is a
win, however, over ths existing Five practice (which *already*
loaded 'site.zcml' from the instance home, if present).

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