Refactoring: Code cleanup

* Delete redundant future imports. Since Galaxy runs on Python >=3.6,
  all future imports are not effective.
* Delete redundant coding comments. Python 3.x uses UTF-8 as a default
  encoding for source files.
* Replace `set([...])` expressions with set literals.
* Replase empty `set([])` expressions with empty set constructor calls.

Signed-off-by: Alexander Saprykin <[email protected]>

galaxy/accounts/migrations/0001_initial.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 import re
 import django.contrib.auth.models

galaxy/accounts/migrations/0002_auto_20150803_1328.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 

galaxy/accounts/migrations/0003_auto_20151125_0840.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/accounts/migrations/0004_customuser_cache_refreshed.py

@@ -1,6 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/accounts/migrations/0005_github_attrs.py

@@ -1,7 +1,3 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11.11 on 2018-04-10 11:09
-from __future__ import unicode_literals
-
 from django.db import migrations, models
 
 

galaxy/accounts/migrations/0006_remove_customuser_github_user.py

@@ -1,7 +1,3 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11.13 on 2018-06-28 17:03
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 

galaxy/accounts/migrations/0007_auto_20180821_1259.py

@@ -1,7 +1,3 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11.15 on 2018-08-21 16:59
-from __future__ import unicode_literals
-
 from django.db import migrations, models
 
 

galaxy/accounts/migrations/0008_auto_20181011_1056.py

@@ -1,7 +1,3 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11.15 on 2018-10-11 14:56
-from __future__ import unicode_literals
-
 from django.db import migrations, models
 
 

galaxy/accounts/migrations/0009_auto_20181018_1248.py

@@ -1,7 +1,3 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11.16 on 2018-10-18 16:48
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 

galaxy/accounts/models.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import unicode_literals
-
 import re
 
 from django.contrib.auth import models as auth_models

galaxy/accounts/tests/test_custom_user_model.py

@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # (c) 2012-2018, Ansible
 # This file is part of Ansible Galaxy
 #

galaxy/api/views/views.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import print_function
-
 import logging
 from collections import OrderedDict
 from allauth.socialaccount.models import SocialToken

galaxy/common/logutils.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import absolute_import
-
 import logging
 
 from galaxy import constants

galaxy/common/version.py

@@ -14,7 +14,6 @@
 #
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
-from __future__ import unicode_literals
 
 import subprocess
 

galaxy/constants.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import unicode_literals
-
 import enum
 import logging
 import re

galaxy/importer/collection.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import absolute_import
-
 import os
 import logging
 

galaxy/importer/repository.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import absolute_import
-
 import logging
 
 from galaxy import constants

galaxy/importer/utils/ast.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import absolute_import
-
 import ast
 
 import yaml

galaxy/main/management/commands/refresh_role_counts.py

@@ -15,8 +15,6 @@
 # You should have received a copy of the Apache License
 # along with Galaxy.  If not, see <http://www.apache.org/licenses/>.
 
-from __future__ import print_function
-
 import time
 import logging
 

galaxy/main/migrations/0001_initial.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 import galaxy.main.mixins
 from django.conf import settings
@@ -406,9 +404,9 @@ class Migration(migrations.Migration):
             options={'verbose_name_plural': 'UserAliases'},
         ),
         migrations.AlterUniqueTogether(
-            name='rolerating', unique_together=set([('owner', 'role')])
+            name='rolerating', unique_together={('owner', 'role')}
         ),
         migrations.AlterUniqueTogether(
-            name='role', unique_together=set([('owner', 'name')])
+            name='role', unique_together={('owner', 'name')}
         ),
     ]

galaxy/main/migrations/0002_auto_20150824_1342.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 

galaxy/main/migrations/0003_auto_20150824_1354.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0004_auto_20150824_1430.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 import math

galaxy/main/migrations/0005_auto_20150824_1444.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 from galaxy.api.aggregators import AvgWithZeroForNull

galaxy/main/migrations/0006_auto_20150825_1720.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 
@@ -14,6 +12,6 @@ class Migration(migrations.Migration):
     operations = [
         migrations.AlterIndexTogether(
             name='platform',
-            index_together=set([('id', 'name')]),
+            index_together={('id', 'name')},
         ),
     ]

galaxy/main/migrations/0007_auto_20150825_1723.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 
@@ -14,6 +12,6 @@ class Migration(migrations.Migration):
     operations = [
         migrations.AlterIndexTogether(
             name='platform',
-            index_together=set([('name', 'id')]),
+            index_together={('name', 'id')},
         ),
     ]

galaxy/main/migrations/0008_auto_20150825_1737.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 
@@ -14,6 +12,6 @@ class Migration(migrations.Migration):
     operations = [
         migrations.AlterIndexTogether(
             name='platform',
-            index_together=set([]),
+            index_together=set(),
         ),
     ]

galaxy/main/migrations/0009_auto_20150826_0829.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0010_auto_20150826_1017.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0014_auto_20150917_1211.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations, IntegrityError
 
 import galaxy.main.fields

galaxy/main/migrations/0015_auto_20150917_1504.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0016_auto_20150922_1041.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0017_auto_20151104_1700.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0018_auto_20151104_1701.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 

galaxy/main/migrations/0019_auto_20151113_0936.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 import galaxy.main.mixins
 from django.conf import settings

galaxy/main/migrations/0020_auto_20151118_1350.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0021_auto_20151118_1425.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0022_auto_20151118_1642.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import migrations
 
 

galaxy/main/migrations/0023_auto_20151119_2020.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0024_importtask_finished.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0025_auto_20151120_1006.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0026_auto_20151122_0827.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 from django.conf import settings
 import galaxy.main.fields

galaxy/main/migrations/0027_auto_20151125_0009.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0028_auto_20151125_1231.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations
 
 

galaxy/main/migrations/0029_importtask_github_branch.py

@@ -1,7 +1,5 @@
 # NOTE(cutwater): This migration is replaced by v2_4_0 and should be
 #   deleted once superseding migration is merged into master.
-from __future__ import unicode_literals
-
 from django.db import models, migrations