Remove redundant undefined error message (#81867)

Fixes: #78703

Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>

changelogs/fragments/78703_undefined.yml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+  - Do not print undefined error message twice (https://github.com/ansible/ansible/issues/78703).

lib/ansible/template/__init__.py

@@ -1011,10 +1011,14 @@ class Templar:
                     if unsafe:
                         res = wrap_var(res)
             return res
-        except (UndefinedError, AnsibleUndefinedVariable) as e:
+        except UndefinedError as e:
             if fail_on_undefined:
-                raise AnsibleUndefinedVariable(e, orig_exc=e)
-            else:
+                raise AnsibleUndefinedVariable(e)
+            display.debug("Ignoring undefined failure: %s" % to_text(e))
+            return data
+        except AnsibleUndefinedVariable as e:
+            if fail_on_undefined:
+                raise
             display.debug("Ignoring undefined failure: %s" % to_text(e))
             return data
 

test/integration/targets/template/tasks/main.yml

@@ -714,7 +714,7 @@
 
 - name: check that proper error message is emitted when in operator is used
   assert:
-    that: "\"'y' is undefined\" in error.msg"
+    that: "\"The error was: 'y' is undefined\n\n\" in error.msg"
 
 - template:
     src: template_import_macro_globals.j2