mock and local repo cache

[Michael A. Peters]

neither package foo nor bar are in an existing repo that mock can see.
package bar BuildRequires package foo-devel

mock builds foo and then I put it the results local repo and run createrepo
then attempt to mock build bar and build fails because it can not find 
package foo-devel.

if I manually delete the mock cache for the local repo, then mock finds 
foo-devel and builds bar.

I did not have this problem with the old version of mock from CentOS

Is there a way to configure mock to not cache the local repo?