Fix bugs related to task_includes and dep chain inheritance

* Fix the way task_include fields were created and copied
* Have blocks get_dep_chain() look at task_include's blocks for proper
  dep chain inheritance
* Fix the way task_include fields are copied to prevent a recursive
  degradation

Fixes #14460

lib/ansible/playbook/block.py

@@ -153,6 +153,8 @@ class Block(Base, Become, Conditional, Taggable):
         if self._dep_chain is None:
             if self._parent_block:
                 return self._parent_block.get_dep_chain()
+            elif self._task_include:
+                return self._task_include._block.get_dep_chain()
             else:
                 return None
         else:
@@ -193,7 +195,8 @@ class Block(Base, Become, Conditional, Taggable):
 
         new_me._task_include = None
         if self._task_include:
-            new_me._task_include = self._task_include.copy()
+            new_me._task_include = self._task_include.copy(exclude_block=True)
+            new_me._task_include._block = self._task_include._block.copy(exclude_tasks=True)
 
         return new_me
 
@@ -374,7 +377,7 @@ class Block(Base, Become, Conditional, Taggable):
             return tmp_list
 
         def evaluate_block(block):
-            new_block = self.copy()
+            new_block = self.copy(exclude_tasks=True)
             new_block.block  = evaluate_and_append_task(block.block)
             new_block.rescue = evaluate_and_append_task(block.rescue)
             new_block.always = evaluate_and_append_task(block.always)

lib/ansible/plugins/strategy/__init__.py

@@ -452,7 +452,7 @@ class StrategyBase:
             block_list = load_list_of_blocks(
                 data,
                 play=included_file._task._block._play,
-                parent_block=included_file._task._block,
+                parent_block=None,
                 task_include=included_file._task,
                 role=included_file._task._role,
                 use_handlers=is_handler,
@@ -478,11 +478,7 @@ class StrategyBase:
         # set the vars for this task from those specified as params to the include
         for b in block_list:
             # first make a copy of the including task, so that each has a unique copy to modify
-            # FIXME: not sure if this is the best way to fix this, as we might be losing
-            #        information in the copy. Previously we assigned the include params to
-            #        the block variables directly, which caused other problems, so we may
-            #        need to figure out a third option if this also presents problems.
-            b._task_include = b._task_include.copy(exclude_block=True)
+            b._task_include = b._task_include.copy()
             # then we create a temporary set of vars to ensure the variable reference is unique
             temp_vars = b._task_include.vars.copy()
             temp_vars.update(included_file._args.copy())