Fixup Python 3 test failures.

requests/sessions.py

@@ -136,8 +136,8 @@ class SessionRedirectMixin(object):
             # urlparse in requote_uri will encode it with UTF-8 before quoting.
             # Because of this insanity, we need to fix it up ourselves by
             # sending the URL back to bytes ourselves.
-            if is_py3 and isinstance(url, str):
-                url = url.encode('latin1')
+            if is_py3 and isinstance(location_url, str):
+                location_url = location_url.encode('latin1')
 
             # Facilitate relative 'location' headers, as allowed by RFC 7231.
             # (e.g. '/path/to/resource' instead of 'http://domain.tld/path/to/resource')

test_requests.py

@@ -1653,7 +1653,7 @@ class TestRedirects:
             assert session.calls[-1] == send_call
 
     @pytest.mark.skipif(is_py2, reason="requires python 3")
-    def test_redirects_with_latin1_header(self):
+    def test_redirects_with_latin1_header(self, httpbin):
         """Test that redirect headers decoded with Latin 1 are correctly
         followed"""
         session = RedirectSession([303])