Fixed forward creation from import.

see #1144

modoboa/admin/models/alias.py

@@ -186,7 +186,7 @@ class Alias(AdminObject):
             sender="import", context=user, klass=Alias)
         core_signals.can_create_object.send(
             sender="import", context=domain, object_type="mailbox_aliases")
-        if Alias.objects.filter(address=address).exists():
+        if Alias.objects.filter(address=address, internal=False).exists():
             raise Conflict
         self.address = address
         self.domain = domain

modoboa/admin/tests/test_import_.py

@@ -83,7 +83,8 @@ domainalias;test.alias;test.com;True
                 "sourcefile": f
             }
         )
-        self.assertIn('Object already exists: domainalias', resp.content.decode())
+        self.assertIn(
+            "Object already exists: domainalias", resp.content.decode())
 
     def test_identities_import(self):
         response = self.client.get(reverse("admin:identity_import"))
@@ -274,3 +275,16 @@ alias;user.alias@test.com;True;user@test.com;;;;;;;;;;;;;;;;
         )
         alias = Alias.objects.get(address="user.alias@test.com")
         self.assertEqual(alias.type, "alias")
+
+    def test_import_account_alias_conflict(self):
+        """Specific test for #1144."""
+        f = ContentFile(b"""
+alias;user@test.com;True;admin@test.com
+""", name="identities.csv")
+        self.client.post(
+            reverse("admin:identity_import"),
+            {"sourcefile": f, "crypt_password": True}
+        )
+        self.assertTrue(
+            Alias.objects.filter(
+                address="user@test.com", internal=False).exists())