I should also note that a slapcat of the config database fails too in the exact same manner.
I'm guessing this is somehow related to the fact that the chain module/overlay is located within the back_ldap module, but I'm not sure how to work around the issue yet, so at this time slapd will not start on the slave server on which slapd was stopped after adding the chaining configuration as is documented in test022-ppolicy.