xml: fix predicated xpath no-match incorrectly creating nodes (#12031)

* fix(xml): no-op when predicated xpath finds no match instead of creating nodes

When using xpath like element[text()='old'] with value=new, a no-match due
to the predicate not being satisfied incorrectly triggered node creation,
corrupting the XML. Now treats predicate misses as a no-op.

Fixes #8730

* changelog(xml): add fragment for PR #12031

* fix(xml): remove spurious test-unset-element-value include from main.yml

That file belongs to a different branch and was accidentally dragged in
during a stash conflict resolution.

* feat(xml): add create_if_missing option to control node creation on value no-match

Instead of implicitly creating nodes when value is set and xpath finds no match,
expose create_if_missing (default true, preserving old behavior) so callers
can opt into a silent no-op with create_if_missing=false.

Fixes #8730

plugins/modules/xml.py

@@ -144,6 +144,13 @@ options:
       - This parameter requires O(xpath) to be set.
     type: bool
     default: false
+  create_if_missing:
+    description:
+      - When using O(value) and the O(xpath) matches no nodes, create the node.
+      - When set to V(false), a no-match is silently ignored instead of creating a new node.
+    type: bool
+    default: true
+    version_added: "13.0.0"
 requirements:
   - lxml >= 2.3.0
 notes:
@@ -673,11 +680,13 @@ def ensure_xpath_exists(module, tree, xpath, namespaces):
     finish(module, tree, xpath, namespaces, changed)
 
 
-def set_target_inner(module, tree, xpath, namespaces, attribute, value):
+def set_target_inner(module, tree, xpath, namespaces, attribute, value, create_if_missing=True):
     changed = False
 
     try:
         if not is_node(tree, xpath, namespaces):
+            if not create_if_missing:
+                return changed
             changed = check_or_make_target(module, tree, xpath, namespaces)
     except Exception as e:
         missing_namespace = ""
@@ -722,8 +731,8 @@ def set_target_inner(module, tree, xpath, namespaces, attribute, value):
     return changed
 
 
-def set_target(module, tree, xpath, namespaces, attribute, value):
-    changed = set_target_inner(module, tree, xpath, namespaces, attribute, value)
+def set_target(module, tree, xpath, namespaces, attribute, value, create_if_missing):
+    changed = set_target_inner(module, tree, xpath, namespaces, attribute, value, create_if_missing)
     finish(module, tree, xpath, namespaces, changed)
 
 
@@ -895,6 +904,7 @@ def main():
             huge_tree=dict(type="bool", default=False),
             insertbefore=dict(type="bool", default=False),
             insertafter=dict(type="bool", default=False),
+            create_if_missing=dict(type="bool", default=True),
         ),
         supports_check_mode=True,
         required_by=dict(
@@ -939,6 +949,7 @@ def main():
     huge_tree = module.params["huge_tree"]
     insertbefore = module.params["insertbefore"]
     insertafter = module.params["insertafter"]
+    create_if_missing = module.params["create_if_missing"]
 
     # Check if we have lxml 2.3.0 or newer installed
     if not HAS_LXML:
@@ -1014,7 +1025,7 @@ def main():
 
     # Is the xpath target an attribute selector?
     if value is not None:
-        set_target(module, doc, xpath, namespaces, attribute, value)
+        set_target(module, doc, xpath, namespaces, attribute, value, create_if_missing)
 
     # If an xpath was provided, we need to do something with the data
     if xpath is not None: