Fix ec2_group for EC2-Classic accounts (#46242)

* Fix ec2_group for EC2-Classic accounts

* changelog

(cherry picked from commit 9efc3dc761)

changelogs/fragments/fix_ec2_group_vpc_precedence_classic.yaml

@@ -0,0 +1,7 @@
+---
+bugfixes:
+  - The patch fixing the regression of no longer preferring matching security
+    groups in the same VPC https://github.com/ansible/ansible/pull/45787
+    (which was also backported to 2.6) broke EC2-Classic accounts.
+    https://github.com/ansible/ansible/pull/46242 removes the assumption that
+    security groups must be in a VPC.

lib/ansible/modules/cloud/amazon/ec2_group.py

@@ -837,7 +837,7 @@ def group_exists(client, module, vpc_id, group_id, name):
         groups = dict((group['GroupId'], group) for group in all_groups)
         groups.update(dict((group['GroupName'], group) for group in all_groups))
         if vpc_id:
-            vpc_wins = dict((group['GroupName'], group) for group in all_groups if group['VpcId'] == vpc_id)
+            vpc_wins = dict((group['GroupName'], group) for group in all_groups if group.get('VpcId') and group['VpcId'] == vpc_id)
             groups.update(vpc_wins)
         # maintain backwards compatibility by using the last matching group
         return security_groups[-1], groups