fixed flush_message test which i broke while merging two versions of it
fixed flush_message test which i broke while merging two versions of it

caktus/rapidsms,catalpainternational/rapidsms,ehealthafrica-ci/rapidsms,dimagi/rapidsms,lsgunth/rapidsms,eHealthAfrica/rapidsms,dimagi/rapidsms,ken-muturi/rapidsms,ken-muturi/rapidsms,catalpainternational/rapidsms,dimagi/rapidsms-core-dev,lsgunth/rapidsms,unicefuganda/edtrac,unicefuganda/edtrac,rapidsms/rapidsms-core-dev,peterayeni/rapidsms,dimagi/rapidsms-core-dev,catalpainternational/rapidsms,catalpainternational/rapidsms,ken-muturi/rapidsms,caktus/rapidsms,lsgunth/rapidsms,caktus/rapidsms,peterayeni/rapidsms,lsgunth/rapidsms,unicefuganda/edtrac,peterayeni/rapidsms,ehealthafrica-ci/rapidsms,eHealthAfrica/rapidsms,peterayeni/rapidsms,rapidsms/rapidsms-core-dev,ehealthafrica-ci/rapidsms,eHealthAfrica/rapidsms