There isn't a Fedora 18 repo yet. All he has up are Fedora 16 and Fedora 17.
Try this to get your system update:
yum --disablerepo=home_zhonghuaren update
And no, you wouldn't file this with the Redhat bugzilla since it's a third party repo that is your problem. You need to resolve that with whoever maintains the third party repo.
This is a repo for Fedora packages, not opensuse packages. The repo is hosted on the opensuse servers, but it's a Fedora repo.
To actually upgrade to Fedora 18, you will probably need to edit the repo file in /etc/yum.repos.d and disable the repo there.