[Zope] Upgrading to Zope 2.9.1

[Brian Sullivan]

I am in the process of testing an upgrade from a Zope 2.8.4 system  to
a Zope 2.9.1 system.

The process I used:

1) Install 2.9.1 on a Win2003 system (it happens to be the same one
that the 2.8.4 system is running but I changed the config so the ports
don't conflict). The installation is successful

2) Copy the Product directory from my functioning 2.8.4 system
instance to the 2.9.1 instance

3) copy the ZODB from the functioning 2.8.4 system to the 2.9.1 system

All appears to go well -- the 2.9.1 system appears to be running
everything from the 2.8.4 system correctly. A deeper check though
shows that a few Python scripts in the ZODB (this in a system that has
20 or 30 scripts) fail. Examining the scripts indicates an error at
line 3 -- but no such error can be found, however saving the script
with no changes eliminates the error and also causes the script to now
function.

After finding and correcting these scripts everything seems to be working well.

Any idea what happened during the upgrade to cause this strange
behaviour and how can I avoid it?

I will have to go through a similar upgrade at a customer's site and
would like to avoid hand checking every script if I can avoid it.