Replace:
<extension point="org.eclipse.team.core.projectSets">
<projectSets id="org.eclipse.team.cvs.core.cvsnature" class="org.eclipse.team.internal.ccvs.ui.CVSProjectSetSerializer"/>
</extension>
with
<extension point="org.eclipse.team.core.repository">
<repository
typeClass="org.eclipse.team.internal.ccvs.core.CVSTeamProviderType"
class="org.eclipse.team.internal.ccvs.core.CVSTeamProvider"
id="org.eclipse.team.cvs.core.cvsnature">
</repository>
</extension>
It also requires a a new class/-s for eclipse clearcase plugin.
//mike
Diff: