molecule lint fails due to local module from dependent role not found

[beenje]

Issue Type

• Bug report

Molecule and Ansible details

ansible --version && molecule --version
ansible 2.9.11
  config file = /Users/benjaminbertrand/.ansible.cfg
  configured module search path = ['/Users/benjaminbertrand/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /Users/benjaminbertrand/miniconda3/envs/molecule3/lib/python3.6/site-packages/ansible
  executable location = /Users/benjaminbertrand/miniconda3/envs/molecule3/bin/ansible
  python version = 3.6.11 | packaged by conda-forge | (default, Aug  5 2020, 20:19:23) [GCC Clang 10.0.1 ]
molecule 3.0.8

Molecule installation method (one of):

• pip

Ansible installation method (one of):

• pip

Detail any linters or test runners used:

lint: |
  set -e
  yamllint .
  ansible-lint
  flake8

Desired Behavior

I just switched from molecule 2 to molecule 3.
I have a role with a local module:

role-a/library/conda.py

role-b has role-a as dependency and uses the conda module.

Running molecule lint should just work. It did with molecule 2.

Actual Behaviour

Running molecule lint fails because the conda module can't be found:

CRITICAL Couldn't parse task at /Users/.../role-b/tasks/main.yml:19 (couldn't resolve module/action 'conda'. This often indicates a misspelling, missing collection, or incorrect module path.)

In molecule 2, I noticed that ANSIBLE_ROLES_PATH was set when running molecule lint.
Setting it like that in my molecule.yml works but seems hacky:

lint: |
  set -e
  yamllint .
  ANSIBLE_ROLES_PATH=${MOLECULE_EPHEMERAL_DIRECTORY}/roles ansible-lint
  flake8

Could ANSIBLE_ROLES_PATH be set automatically when running molecule lint? Or do you have another suggestion?