No idempotency on "install ruby versions for system"

[marcinhlybin]

A role does not have idempotency which is essential feature of Ansible.
Following task always shows changed:

TASK [zzet.rbenv : install ruby versions for system] *********************************************************************************************************
changed: [dev-02] => (item={u'version': u'2.5.1'})

Role variables:

    rbenv:
      env: system
      version: v1.1.1
      default_ruby: 2.5.1
      rubies:
        - version: 2.5.1

[ramonrails]

TASK [zzet.rbenv : check ruby versions installed for system] ********************************************************************************************************
ok: [staging] => (item={'version': '2.7.1', 'env': {'RUBY_CONFIGURE_OPTS': '--enable-shared'}})

TASK [zzet.rbenv : install ruby versions for system] ****************************************************************************************************************
changed: [staging] => (item={'version': '2.7.1', 'env': {'RUBY_CONFIGURE_OPTS': '--enable-shared'}})