Allow FieldAttribute lists and sets to be set from a comma separated string

lib/ansible/playbook/base.py

@@ -334,6 +334,9 @@ class Base:
                         if value is None:
                             value = []
                         elif not isinstance(value, list):
+                            if isinstance(value, string_types):
+                                value = value.split(',')
+                            else:
                                 value = [ value ]
                         if attribute.listof is not None:
                             for item in value:
@@ -346,8 +349,12 @@ class Base:
                     elif attribute.isa == 'set':
                         if value is None:
                             value = set()
+                        elif not isinstance(value, (list, set)):
+                            if isinstance(value, string_types):
+                                value = value.split(',')
                             else:
-                            if not isinstance(value, (list, set)):
+                                # Making a list like this handles strings of
+                                # text and bytes properly
                                 value = [ value ]
                         if not isinstance(value, set):
                             value = set(value)