Admin user can't change reader user's password

[edmundoa]

Trying to change a reader's user password fails with the message: Error! Could not update the password. Full error message from the log:

[error] o.g.r.m.User - Unable to update password
org.graylog2.restclient.lib.APIException: API call failed PUT http://@127.0.0.1:12900/users/reader/password returned 400 Bad Request body: Instantiation of [simple type, class org.graylog2.rest.resources.users.requests.ChangePasswordRequest] value failed: Null oldPassword (through reference chain: org.graylog2.rest.resources.users.requests.ChangePasswordRequest["password"])
        at org.graylog2.restclient.lib.ApiClientImpl$ApiRequestBuilder.execute(ApiClientImpl.java:481) ~[org.graylog2.graylog2-rest-client-1.0.0-beta.4-SNAPSHOT.jar:na]
        at org.graylog2.restclient.models.User.updatePassword(User.java:153) ~[org.graylog2.graylog2-rest-client-1.0.0-beta.4-SNAPSHOT.jar:na]
        at controllers.UsersController.changePassword(UsersController.java:382) [graylog-web-interface.graylog-web-interface-1.0.0-beta.4-SNAPSHOT.jar:1.0.0-beta.4-SNAPSHOT]
        at Routes$$anonfun$routes$1$$anonfun$applyOrElse$106$$anonfun$apply$680.apply(routes_routing.scala:2173) [graylog-web-interface.graylog-web-interface-1.0.0-beta.4-SNAPSHOT.jar:na]
        at Routes$$anonfun$routes$1$$anonfun$applyOrElse$106$$anonfun$apply$680.apply(routes_routing.scala:2173) [graylog-web-interface.graylog-web-interface-1.0.0-beta.4-SNAPSHOT.jar:na]