DUB Bash Completion

["Nordlöw" via Digitalmars-d-announce]

On Sunday, 13 July 2014 at 20:15:06 UTC, w0rp wrote:
> I suppose one extra step you could go would be to somehow 
> complete --config= too, so you could tab complete --config=foo 
> and --config=bar or something.

     --config

is not documented by

     dub -h

Is it a sub command flag?