Implemented a safe way to delete constraints, as these constraints didn't exist. It's most likely got to do with the PG upgrade from 7.2 to 7.3 not recording constraints properly. This is a workaround, not a fix. See bug #1294.
Fixed bug #1465: The upgrade script mistakenly put in a funtion name for the name_method for weblogger_channels, but the function itself didn't exist; the create-script didn't have this.