Warnings when deleting a site

When we delete a site, we see this in the task log

Argument 1 passed to provisionService_db_mysql::grant_host() must be an instance of provisionServer, instance of provisionContext_server given mysql_service.inc:90
Argument 1 passed to provisionService_db_mysql::grant_host() must be an instance of provisionServer, instance of provisionContext_server given mysql_service.inc:90

This might also be the problem behind #940860: Drupal 7.0 Beta 1 Problems as the errors there occur right after dropping the database, but apparently before revoking the grant.