We really want to manipulate bytes objects here

coin/members/models.py

@@ -140,7 +140,8 @@ class Member(CoinLdapSyncMixin, AbstractUser):
         username = unicodedata.normalize('NFD', username)\
             .encode('ascii', 'ignore')
         # Enlever ponctuation et espace
-        username = username.translate(None, string.punctuation + ' ')
+        punctuation = (string.punctuation + ' ').encode('ascii')
+        username = username.translate(None, punctuation)
         # En minuscule
         username = username.lower()
         # Maximum de 30 char