[Yum] repository specific package excludes

[Michael A. Peters]

Is it possible (preferably a configuration option) to tell yum to  
ignore a package from a specific repository?

Say for example two repositories contain the package foobar, but I only  
want updates to foobar if they come from repository A and I don't want  
updates to foobar from repository B.

If this functionallity isn't there, is this something I should add to  
the yum bugzilla as a feature request?