--- Lib/configparser.py.orig	2014-04-16 14:28:16.406648591 -0400
+++ Lib/configparser.py	2014-04-16 14:32:50.078662782 -0400
@@ -865,9 +865,9 @@
             return (option in self._sections[section]
                     or option in self._defaults)
 
-    def set(self, section, option, value=None):
+    def set(self, section, option, value=None, raw=False):
         """Set an option."""
-        if value:
+        if value and not raw:
             value = self._interpolation.before_set(self, section, option,
                                                    value)
         if not section or section == self.default_section:
@@ -1160,11 +1160,12 @@
 
     _DEFAULT_INTERPOLATION = BasicInterpolation()
 
-    def set(self, section, option, value=None):
+    def set(self, section, option, value=None, raw=False):
         """Set an option.  Extends RawConfigParser.set by validating type and
         interpolation syntax on the value."""
-        self._validate_value_types(option=option, value=value)
-        super().set(section, option, value)
+        if not raw:
+          self._validate_value_types(option=option, value=value)
+        super().set(section, option, value, raw)
 
     def add_section(self, section):
         """Create a new section in the configuration.  Extends
--- Lib/test/test_configparser.py.orig	2014-04-16 14:29:44.246653146 -0400
+++ Lib/test/test_configparser.py	2014-04-16 15:11:09.458782015 -0400
@@ -1764,5 +1764,28 @@
         self.assertEqual(s['k3'], 'v3;#//still v3# and still v3')
 
 
+class RawParameterAsymmetryTestCase(unittest.TestCase):
+    '''
+    Tests for issue #21265: ConfigParser can read values with
+    interpolation syntax violations (via `raw` parameter), but cannot
+    set them.
+    '''
+
+    def test_raw_value_get(self):
+        cfg = configparser.ConfigParser()
+        cfg.read_string('[time]\nfmt = %H:%M:%S\n')
+        self.assertEqual(cfg.get('time', 'fmt', raw=True), '%H:%M:%S')
+        with self.assertRaises(configparser.InterpolationSyntaxError) as cm:
+            cfg.get('time', 'fmt')
+
+    def test_raw_value_set(self):
+        cfg = configparser.ConfigParser()
+        cfg.add_section('time')
+        cfg.set('time', 'fmt', '%I:%M %p', raw=True)
+        self.assertEqual(cfg.get('time', 'fmt', raw=True), '%I:%M %p')
+        with self.assertRaises(configparser.InterpolationSyntaxError) as cm:
+            cfg.get('time', 'fmt')
+
+
 if __name__ == '__main__':
     unittest.main()