This worked for me on a test server, but I haven't actually tried the 5.0 upgrade for real. I'm waiting for 5.0.1. YMMV...
I traded emails with hughesjr, and he suggests that this is a 'safe' way to downgrade perl 5.8.8 to perl 5.8.5 using rpm --nodeps is as follows:
Just to be safe, stop anything you think might be related to perl including zimbra
Check your perl verison
#perl -v
This is perl, v5.8.8 built for i386-linux-thread-multi
#sudo rpm -e --nodeps perl-5.8.8-4.el4s1
(also uninstall perl-suid if you have it installed)
#sudo vi /etc/yum.repos.d/CentOS-Base.repo (add 'exclude=perl*' under [centosplus])
#sudo yum install perl (for me this also added perl-Filter through yum dependency checking)
#sudo reboot
#perl -v
This is perl, v5.8.5 built for i386-linux-thread-multi
After these steps, check if the directory or any code is left in /usr/lib/perl5/5.8.8/* That directory shouldn't exist, but if it does, then you had some perl stuff that depended on 5.8.8 in there that you should look into (reinstall for 5.8.5).
EDIT: Another item to check: View this list of RPM's that are included with CentOS Plus since they are all built against perl 5.8.8 and may have issues after downgrading perl. Check and see if you are using any of them. You may need to uninstall these RPM's and reinstall the base versions. Check here:
Index of /centos/5/centosplus/i386/RPMS (if using x86_64, change URL)
Hope this helps someone out!
Regards,
John