can't add access roles to node in filesystem connector

gistfile1.txt

curl -X POST -H "Content-Type: application/json" --data-binary "@reader_
role.txt" "http://testadmin:password@localhost:8080/rest/auth/fcr:accessroles"

reader_role.txt
{"testuser":["reader"]}

DEBUG 17:44:49.063 (SessionFactory) Returning an authenticated session in the default workspace
DEBUG 17:44:49.063 (ServletContainerAuthenticationProvider) in authenticate: org.modeshape.jcr.api.ServletCredentials@62d83ce1; FAD: org.fcrepo.auth.roles.basic.BasicRolesAuthorizationDelegate@a5a0ef3
DEBUG 17:44:49.095 (AccessRoles) POST Received request param: (POST /rest/auth/fcr:accessroles)@1896334181 org.eclipse.jetty.server.Request@7107c365
DEBUG 17:44:49.095 (FedoraFileSystemConnector) Getting Federated document: /
WARN 17:44:49.098 (FedoraFileSystemConnector) The file system external source "auth-1" does not support namespaces in file/folder names. The namespace "http://fedora.info/definitions/v4/authorization#" will be ignored by the connector on document "/rbacl" for child "authz:rbacl" under "/"
WARN 17:44:49.099 (FedoraFileSystemConnector) The file system external source "auth-1" does not support namespaces in file/folder names. The namespace "http://fedora.info/definitions/v4/authorization#" will be ignored by the connector on document "/rbacl/assignment" for child "authz:assignment" under "/rbacl"
DEBUG 17:44:49.104 (FedoraFileSystemConnector) Getting Federated document: /
DEBUG 17:44:49.107 (FedoraFileSystemConnector) Getting Federated document: /
DEBUG 17:44:49.293 (AccessRoles) Saved access roles {testuser=[reader]}
DEBUG 17:44:49.297 (ServletContainerAuthenticationProvider) in authenticate: null; FAD: org.fcrepo.auth.roles.basic.BasicRolesAuthorizationDelegate@a5a0ef3
DEBUG 17:44:49.305 (FedoraFileSystemConnector) Getting Federated document: /
DEBUG 17:44:49.306 (FedoraFileSystemConnector) Getting Federated document: /rbacl
DEBUG 17:44:49.308 (FedoraFileSystemConnector) Getting Federated document: /rbacl/assignment