Can't update "Host system"

This is the output when running the command from SSH.

   core-ssh:~# hassio -d ho update
    DEBUG [CmdHost]: action->'update', endpoint='update', serverOverride->'', GET->'false', options->'', rawjson->'false', filter->''
    DEBUG [ExecCommand]: basepath->'host', endpoint->'update', serverOverride->'', get->'false', Options->'', Filter->'', RawJSON->'false'
    DEBUG [GenerateURI]: basepath->'host', endpoint->'update', serverOverride->''
    DEBUG [RestCall]: data->'http://hassio/host/update', GET->'false', payload->''
    DEBUG [RestCall]: ResponseBody->'{"result": "error", "message": null}'
    panic: interface conversion: interface is nil, not string

    goroutine 1 [running]:
    panic(0x2c5f60, 0x1070b860)
            /home/travis/.gimme/versions/go1.7.6.linux.amd64/src/runtime/panic.go:500 +0x33c, 0x24, 0x200, 0x0)
            /home/travis/gopath/src/ +0x3c8, 0x4, 0x7ea6ae5d, 0x6, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
            /home/travis/gopath/src/ +0x308
            /home/travis/gopath/src/ +0x538, 0x323758, 0x10778420, 0x0, 0x0)
            /home/travis/gopath/src/ +0xf0, 0x4, 0x0, 0x0, 0x409d20, 0x1, 0x1, 0x2fd4e2, 0x22, 0x0, ...)
            /home/travis/gopath/src/ +0x6b8*App).Run(0x107648c0, 0x1070a160, 0x4, 0x4, 0x0, 0x0)
            /home/travis/gopath/src/ +0x8b0
            /home/travis/gopath/src/ +0x108

I have, what seems to be, the same problem: