Move circular include logic to a separate function

testdata/includes_multi_level/Taskfile.yml

@@ -6,7 +6,4 @@ includes:
 tasks:
   default:
     cmds:
-      - echo "called_dep" > called_dep.txt
-  level1:
-    cmds:
-      - echo "hello level 1"
+      - task: one:two:default

testdata/includes_multi_level/one/Taskfile.yml

@@ -4,6 +4,6 @@ includes:
   'two': ./two/Taskfile.yml
 
 tasks:
-  level2:
+  level1:
     cmds:
-      - echo "hello level 2"
+      - echo "hello level 1"

testdata/includes_multi_level/one/two/Taskfile.yml

@@ -1,6 +1,6 @@
 version: '3'
 
 tasks:
-  level3:
+  default:
     cmds:
-      - echo "hello level 3"
+      - echo "called_dep" > called_dep.txt