Make sure namespaced variable ::acs::db_pools is created before accessing itThis is needed when upgrading from openacs versions that didn't use this variable before
it seems, we can reactivate per-request caching for sitenodes, otherwise we see up to 37 locks per requests on get_node_id on openacs.org (regression test works fine)
Fix attribute::delete proc so it leverages stored procedure capability of dropping the database table as well (was broken before)This is needed for a non-xotcl portable way of dropping acs_attributes
fix site-node test in regression testdon't use per-request caching, since we migh shoot in our own footinterrupt cache_transaction to achieve desired semanticsallow in a few cases empty node_ids for method "get_url" as it is used by current OpenACS