E206: Avoid false positives with multilines

- Fix regression caused by recent refactoring or rule on multilines
- Adds tests for preventing future regression
- Makes the error message mention the failure variable so user
  is not confused (reported line is the first of task, not the
  exact location within)

examples/playbooks/206.yml

@@ -35,3 +35,14 @@
     - name: JSON inside jinja is valid
       debug:
         msg: "{{ {'test': {'subtest': variable}} }}"
+    - name: Avoid false positive on multiline
+      vars:
+        cases:
+          case1: >-
+            http://example.com/{{
+              case1 }}
+          case2: >-
+            http://example.com/{{
+            case2 }}
+      debug:
+        var: cases

src/ansiblelint/rules/VariableHasSpacesRule.py

@@ -11,21 +11,23 @@
 
 class VariableHasSpacesRule(AnsibleLintRule):
     id = '206'
-    shortdesc = 'Variables should have spaces before and after: {{ var_name }}'
+    base_msg = 'Variables should have spaces before and after: '
+    shortdesc = base_msg + ' {{ var_name }}'
     description = 'Variables should have spaces before and after: ``{{ var_name }}``'
     severity = 'LOW'
     tags = ['formatting']
     version_added = 'v4.0.0'
 
-    variable_syntax = re.compile(r"{{.*}}")
-    bracket_regex = re.compile(r"{{[^{' -]|[^ '}-]}}")
+    bracket_regex = re.compile(
+        r"{{[^{\n' -]|[^ '\n}-]}}", re.MULTILINE | re.DOTALL)
+    exclude_json_re = re.compile(r"[^{]{'\w+': ?[^{]{.*?}}")
 
     def matchtask(self, task: Dict[str, Any]) -> Union[bool, str]:
         for k, v in nested_items(task):
             if isinstance(v, str):
-                line_exclude_json = re.sub(r"[^{]{'\w+': ?[^{]{.*?}}", "", v)
-                if bool(self.bracket_regex.search(line_exclude_json)):
-                    return True
+                cleaned = self.exclude_json_re.sub("", v)
+                if bool(self.bracket_regex.search(cleaned)):
+                    return self.base_msg + v
         return False