Don't let lower/upper case throw me off.

Roland Hedberg · Roland Hedberg · commit 086a4d284d6d · 2015-11-16T21:16:02.000+01:00
diff --git a/src/saml2/attribute_converter.py b/src/saml2/attribute_converter.py
@@ -428,7 +428,7 @@ def to_format(self, attr):
             _attr = self._to[attr]
         except KeyError:
             try:
-                _attr = self._to[attr.to_lower()]
+                _attr = self._to[attr.lower()]
             except:
                 _attr = ''
 
