Fix xml issues with python3

Some calls in etree will return bytes where they used to return a string
type.

Author: SpamapS

src/saml2/__init__.py

@@ -674,7 +674,11 @@ def to_string(self, nspair=None):
         return ElementTree.tostring(self._to_element_tree(), encoding="UTF-8")
 
     def __str__(self):
-        return self.to_string()
+        # Yes this is confusing. http://bugs.python.org/issue10942
+        x = self.to_string()
+        if not isinstance(x, six.string_types):
+            x = x.decode('utf-8')
+        return x
 
     def keyswv(self):
         """ Return the keys of attributes or children that has values

src/saml2/pack.py

@@ -175,6 +175,8 @@ def make_soap_enveloped_saml_thingy(thingy, header_parts=None):
         _child.tag = '{%s}FuddleMuddle' % DUMMY_NAMESPACE
         body.append(_child)
         _str = ElementTree.tostring(envelope, encoding="UTF-8")
+        if isinstance(_str, six.binary_type):
+            _str = _str.decode('utf-8')
         logger.debug("SOAP precursor: %s" % _str)
         # find an remove the namespace definition
         i = _str.find(DUMMY_NAMESPACE)

src/saml2/response.py

@@ -4,6 +4,7 @@
 
 import calendar
 import logging
+import six
 from saml2.samlp import STATUS_VERSION_MISMATCH
 from saml2.samlp import STATUS_AUTHN_FAILED
 from saml2.samlp import STATUS_INVALID_ATTR_NAME_OR_VALUE
@@ -942,6 +943,8 @@ def session_info(self):
                     "not_on_or_after": nooa, "authn_info": self.authn_info()}
 
     def __str__(self):
+        if not isinstance(self.xmlstr, six.string_types):
+            return "%s" % self.xmlstr.decode("utf-8")
         return "%s" % self.xmlstr
 
     def verify_attesting_entity(self, address):