I have finally managed to finish investigation of cp -p bug in coreutils which happens in FC5 (glibc-2.4) when /proc fs is not mounted. Here is my email to bug-coreutils mailing list, and here is the (surprisingly quick!) response from coreutils maintainer. Before now, I had an impression that only Gentoo people are fast to respond to bug reports.

The only problem now is I can not access bugzilla.redhat.com to add FC5 bug.

Still, it will take some time to propagate the fix to coreutils release and FC5 update. So in OpenVZ vzctl we are using dirty workaround: instead of cp -p we use cp --preserve=mode,ownership.