Split password setting to separate method

We don't really want possible side effects of post login signal for
changing user language.
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/accounts/models.py

@@ -577,8 +577,15 @@ class Profile(models.Model):
         return self.user.first_name
 
 
+def set_lang(request, profile)
+    """
+    Sets session language based on user preferences.
+    """
+    request.session[LANGUAGE_SESSION_KEY] = profile.language
+
+
 @receiver(user_logged_in)
-def set_lang(sender, request, user, **kwargs):
+def post_login_handler(sender, request, user, **kwargs):
     '''
     Signal handler for setting user language and
     migrating profile if needed.
@@ -605,8 +612,7 @@ def set_lang(sender, request, user, **kwargs):
         )
 
     # Set language for session based on preferences
-    lang_code = profile.language
-    request.session[LANGUAGE_SESSION_KEY] = lang_code
+    set_lang(request, profile)
 
 
 def create_groups(update):

weblate/accounts/views.py

@@ -164,7 +164,7 @@ def user_profile(request):
                 form.save()
 
             # Change language
-            set_lang(request.user, request=request, user=request.user)
+            set_lang(request, request.user.profile)
 
             # Redirect after saving (and possibly changing language)
             response = redirect('profile')