publish update fails for configs with direct published repos (without snapshot)

[karras]

The snapshot update command fails when having publish endpoints, which get published directly (without snapshot), configured:

$ pyaptly -c trusty.yml snapshot update
Traceback (most recent call last):
  File "/usr/local/bin/pyaptly", line 1794, in <module>
    main()
  File "/usr/local/bin/pyaptly", line 775, in main
    args.func(cfg, args)
  File "/usr/local/bin/pyaptly", line 1284, in snapshot
    for cmd in cmd_snapshot(cfg, snapshot_name, snapshot_config)
  File "/usr/local/bin/pyaptly", line 1534, in cmd_snapshot_update
    if is_publish_affected(publish_name, publish_conf_entry)
  File "/usr/local/bin/pyaptly", line 1519, in is_publish_affected
    for snap in publish['snapshots']:
KeyError: 'snapshots'

Example publish endpoint where the repo is published directly:

  icaclient:
    -
      distribution: "stable"
      origin: "icaclient"
      architectures: ["amd64", "i386"]
      components: "main"
      repo: "icaclient"
      automatic-update: true