get_language() isn't reliable here, so we'll clear everything. This works on my local box

lib/l10n/__init__.py

@@ -75,12 +75,10 @@ def activate(locale):
 
     jingo.env.install_gettext_translations(t)
 
-def deactivate():
-    """ Override django's utils.translation.deactivate().  Django continues
-    to cache a catalog even if you call their deactivate().
+def deactivate_all():
+    """ Override django's utils.translation.deactivate_all().  Django continues
+    to cache a catalog even if you call their deactivate_all().
     """
-    locale = django_trans.get_language()
-    django_trans.deactivate()
-    if locale in django_trans._translations:
-        del django_trans._translations[locale]
+    django_trans.deactivate_all()
+    django_trans._translations = {}
 

lib/l10n/tests/tests.py

@@ -25,7 +25,7 @@ def setup():
 def teardown():
     if os.path.isdir(LOCALEDIR):
         shutil.rmtree(LOCALEDIR)
-    l10n.deactivate()
+    l10n.deactivate_all()
 
 
 @with_setup(setup, teardown)
@@ -67,13 +67,13 @@ def test_ungettext():
 
 
 def test_activate():
-    l10n.deactivate()
+    l10n.deactivate_all()
     l10n.activate('fr')
     # This string is from the AMO .po file
     a_text = "My Account"
     p_text = "Mon compte"
     eq_(p_text, _(a_text))
-    l10n.deactivate()
+    l10n.deactivate_all()
 
 
 MO_DATA = '''\