Fix python3 errors.

Makefile

@@ -37,7 +37,7 @@ cipyflakes:
 	${PYFLAKES_IF_AVAILABLE} ${PYFLAKES_WHITELIST}
 
 citests:
-	nosetests ${CI_TESTS} -v --with-xunit --xunit-file=junit-report.xml
+	nosetests ${CI_TESTS} --with-xunit --xunit-file=junit-report.xml
 
 ci: citests cipyflakes
 

requests/models.py

@@ -340,9 +340,9 @@ class Request(object):
             return None
 
         try:
-            fields = self.data.items()
+            fields = list(self.data.items())
         except AttributeError:
-            fields = dict(self.data).items()
+            fields = list(dict(self.data).items())
 
         if isinstance(files, dict):
             files = files.items()