Fix case where text is None.

Author: Nick Barrett

src/onelogin/saml2/response.py

@@ -349,9 +349,10 @@ def get_attributes(self):
             for attr in attribute_node.iterchildren('{%s}AttributeValue' % OneLogin_Saml2_Constants.NSMAP['saml']):
                 # Remove any whitespace (which may be present where attributes are
                 # nested inside NameID children).
-                text = attr.text.strip()
-                if text:
-                    values.append(text)
+                if attr.text:
+                    text = attr.text.strip()
+                    if text:
+                        values.append(text)
 
                 # Parse any nested NameID children
                 for nameid in attr.iterchildren('{%s}NameID' % OneLogin_Saml2_Constants.NSMAP['saml']):