Only check if play.hosts is a template when the play hasn't been finalized (#73941)

* Extend finalized logic to strategy
* Add changelog fragment

changelogs/fragments/73926-is-template-play-hosts.yml

@@ -0,0 +1,3 @@
+bugfixes:
+- Variable Manager - Only check if ``play.hosts`` is a template when the play
+  hasn't been finalized (https://github.com/ansible/ansible/issues/73926)

lib/ansible/playbook/base.py

@@ -180,6 +180,10 @@ class FieldAttributeBase(with_metaclass(BaseMeta, object)):
         # and init vars, avoid using defaults in field declaration as it lives across plays
         self.vars = dict()
 
+    @property
+    def finalized(self):
+        return self._finalized
+
     def dump_me(self, depth=0):
         ''' this is never called from production code, it is here to be used when debugging as a 'complex print' '''
         if depth == 0:

lib/ansible/plugins/strategy/__init__.py

@@ -251,7 +251,7 @@ class StrategyBase:
         if not refresh and all((self._hosts_cache, self._hosts_cache_all)):
             return
 
-        if Templar(None).is_template(play.hosts):
+        if not play.finalized and Templar(None).is_template(play.hosts):
             _pattern = 'all'
         else:
             _pattern = play.hosts or 'all'

lib/ansible/vars/manager.py

@@ -487,7 +487,7 @@ class VariableManager:
             variables['groups'] = self._inventory.get_groups_dict()
             if play:
                 templar = Templar(loader=self._loader)
-                if templar.is_template(play.hosts):
+                if not play.finalized and templar.is_template(play.hosts):
                     pattern = 'all'
                 else:
                     pattern = play.hosts or 'all'