acme_challenge_cert_helper: fail better to avoid crashes in Ansible (#282)

* Prevent acme_challenge_cert_helper triggering a bug in Ansible.

* Add changelog fragment.

changelogs/fragments/282-acme_challenge_cert_helper-error.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- "acme_challenge_cert_helper - only return exception when cryptography is not installed, not when a too old version of it is installed. This prevents Ansible's callback to crash (https://github.com/ansible-collections/community.crypto/pull/281)."

plugins/modules/acme_challenge_cert_helper.py

@@ -202,7 +202,10 @@ def main():
         ),
     )
     if not HAS_CRYPTOGRAPHY:
+        # Some callbacks die when exception is provided with value None
+        if CRYPTOGRAPHY_IMP_ERR:
             module.fail_json(msg=missing_required_lib('cryptography >= 1.3'), exception=CRYPTOGRAPHY_IMP_ERR)
+        module.fail_json(msg=missing_required_lib('cryptography >= 1.3'))
 
     try:
         # Get parameters