Documented feature secrets config=/alternate/secrets/path not implemented

When trying to run a secrets phase from the manifest as:

secrets config=/path/to/my/secrets

The secrets phase still pulls from $MOJO_ROOT/LOCAL/$MOJO_PROJECT/$MOJO_STAGE

Digging through the code, I couldn't find any reference to "config" in the secrets phase.

Workaround is to continue using default directory, but config=/path/to/secrets would be a very nice feature indeed.

I think this would also cause issue with secrets re-gathering during other phases as mentioned in lp#1516478 if the config= wasn't carried through to other phases where re-run of secrets phase is implied.