Comment 1 for bug 1573440

VMware DVS plugin environment_config.yaml
https://github.com/openstack/fuel-plugin-vmware-dvs/blob/master/environment_config.yaml

If comment section:
# regex:
# source: &non_empty_string '\S'
# error: "Empty name of dvSwitch"
the problem is not reproduced.

If i try use another regex:
    regex:
      source: '.'
      error: "Empty name of dvSwitch"
the problem is reproduced.

Сhanges, after which the problem occurred:
https://github.com/openstack/fuel-web/commit/7e3fe2c308918f4f8abc42ad7d1584b4e4afadfc