Code review comment for lp://staging/~allenap/maas/rpc-get-secrets

I'm not going to block it, but I'm not going to approve it either. Out of
interest, what constitutes too much work here?

The tags stuff is also blocked by the problem we talked about yesterday,
namely the GIL block. As I said in the other review I don't think the process
pipe will help as the reader blocks until it closes, so it needs twisted IO
instead (which is why ampoule was created I suspect).

I think that we need to think harder about the architecture of these jobs
rather than throwing RPC at everything. We might want to include API
parameters as part of the RPC call-out to do the job, for example, especially
in the case of the long running jobs where we don't want to wait around. We
can then reactor.spawnProcess() and leave it running and get notified when it
finishes.