app ignores broken app.http.address

[rade]

$ scope launch --app.http.address=mumble
f8c8411acb11203fdb9eb4797ea76c32020ceea295209a611d4a93804774f408
Weave Scope is reachable at the following URL(s):
  * http://192.168.1.65:4040/
  * http://192.168.48.1:4040/

Leaving aside the bogus output - see #1190 - the app is in fact not listening anywhere. The container logs say:

<app> INFO: 2016/03/21 21:23:13.447068 listening on mumble
<app> INFO: 2016/03/21 21:23:13.447166 listen tcp: missing port in address mumble

Surely that should be treated as a fatal error.