[umessage] Work around bug in python 3's decode_header

We sometimes get unicode objects out of that function, on which
.decode() obviously fails. Upstream has apparently not to fix the
existing function, so let's handle it ourselves.

Tests are taken from CubicWeb.  Related to #1716128.

1 files changed, 12 insertions, 0 deletions

diff --git a/test/unittest_umessage.py b/test/unittest_umessage.py
index 531573c..940b308 100644
--- a/test/unittest_umessage.py
+++ b/test/unittest_umessage.py
@@ -60,6 +60,18 @@ class UMessageTC(TestCase):
         self.assertEqual(type(test), text_type)
         self.assertEqual(test, u'Raphaël DUPONT<raphael.dupont@societe.fr>')
 
+    def test_decode_QP_utf8(self):
+        test_line = '=?utf-8?q?o=C3=AEm?= <oim@logilab.fr>'
+        test = decode_QP(test_line)
+        self.assertEqual(type(test), text_type)
+        self.assertEqual(test, u'oîm <oim@logilab.fr>')
+
+    def test_decode_QP_ascii(self):
+        test_line = 'test <test@logilab.fr>'
+        test = decode_QP(test_line)
+        self.assertEqual(type(test), text_type)
+        self.assertEqual(test, u'test <test@logilab.fr>')
+
 
 if __name__ == '__main__':
     unittest_main()