Ansible install does not work

Created by: saurabhchakrabarti

I've started evaluating this project once again after a long break. I'm getting the following error when I try to deploy using ansible

ERROR! no action detected in task. This often indicates a misspelled module name, or incorrect module path.

The error appears to have been in '/etc/ansible/roles/openwisp.openwisp2/tasks/main.yml': line 3, column 3, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

## tasks
- import_tasks: variables.yml
  ^ here


The error appears to have been in '/etc/ansible/roles/openwisp.openwisp2/tasks/main.yml': line 3, column 3, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

## tasks
- import_tasks: variables.yml
  ^ here

Things work when I replace import_tasks with include.

ansible version - 2.3.1.0 Ubuntu 16.04.2 LTS