if random docker-compose file is not present --file option does not work

[sebgoa]

I found out, that even though we use the --file option, we still need to have a somewhat valid docker-compose file present.

sebair: kompose2 (master)$ cat docker-compose.yml 
toto:
  image: toto
sebair: kompose2 (master)$ cat mongo.yml 
mongo:
  image: mongo
sebair: kompose2 (master)$ ./kompose convert -f mongo.yml --stdout
{
  "kind": "ReplicationController",
  "apiVersion": "v1",
  "metadata": {
    "name": "mongo",
    "creationTimestamp": null,
    "labels": {
      "service": "mongo"

if you remove the docker-compose file:

$ ./kompose convert -f mongo.yml --stdout
ERRO[0000] Failed to find docker-compose.yml            
FATA[0000] Failed to read project: open docker-compose.yml: no such file or directory