[1.10.x] Fixed #27058 -- Reallowed the {% for %} tag to unpack any iterable.

Thanks Sergei Maertens for the report and patch.

Backport of 937d752d3d from master

django/template/defaulttags.py

@@ -189,10 +189,10 @@ class ForNode(Node):
                 if unpack:
                     # If there are multiple loop variables, unpack the item into
                     # them.
-                    if not isinstance(item, (list, tuple)):
-                        len_item = 1
-                    else:
+                    try:
                         len_item = len(item)
+                    except TypeError:  # not an iterable
+                        len_item = 1
                     # Check loop variable count before unpacking
                     if num_loopvars != len_item:
                         raise ValueError(

docs/releases/1.10.1.txt

@@ -51,3 +51,5 @@ Bugfixes
 
 * Fixed annotations with database functions when combined with lookups on
   PostGIS (:ticket:`27014`).
+
+* Reallowed the ``{% for %}`` tag to unpack any iterable (:ticket:`27058`).

tests/template_tests/syntax_tests/test_for.py

@@ -126,6 +126,11 @@ class ForTagTests(SimpleTestCase):
         output = self.engine.render_to_string('for-tag-filter-ws', {'s': 'abc'})
         self.assertEqual(output, 'abc')
 
+    @setup({'for-tag-unpack-strs': '{% for x,y in items %}{{ x }}:{{ y }}/{% endfor %}'})
+    def test_for_tag_unpack_strs(self):
+        output = self.engine.render_to_string('for-tag-unpack-strs', {'items': ('ab', 'ac')})
+        self.assertEqual(output, 'a:b/a:c/')
+
     @setup({'for-tag-unpack10': '{% for x,y in items %}{{ x }}:{{ y }}/{% endfor %}'})
     def test_for_tag_unpack10(self):
         with self.assertRaisesMessage(ValueError, 'Need 2 values to unpack in for loop; got 3.'):