Can't invite another user to be owner of a crate

[glueball]

We have a ktra installation in production.
I have a library in ktra, and another user that should be able to update it. I have verified that the username is correct by issuing a login call with cURL. Then I issue the owner cargo command:

$ cargo owner --registry ktra --add username
    Updating `ktra` index
error: failed to invite owners to crate `ktra` on registry at (url)

The ktra executable outputs the following (among other lines):

unable to process request (internal error) status=500 error=Rejection([InvalidLoginNames(["username"])

[gagbo]

For the record (and if anyone else finds this), the error probably was that the username in the cargo command had to be prefixed with ktra-secure-auth: as in

cargo owner --registry ktra --add ktra-secure-auth:username

I had the same issue recently, that's why I pushed moriturus/ktra#29