patch/gerrit: convert to python3 only

All users of these modules are python3 only already.

BUG=chromium:997354
TEST=`./run_tests` passes

Change-Id: Ida242ab0c38caee3262f3bbea0bcb4d57fa9ff3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2646228
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
diff --git a/lib/gerrit.py b/lib/gerrit.py
index aa1e418..b7f4568 100644
--- a/lib/gerrit.py
+++ b/lib/gerrit.py
@@ -8,6 +8,7 @@
 from __future__ import print_function
 
 import operator
+import sys
 
 from chromite.lib import config_lib
 from chromite.lib import constants
@@ -19,6 +20,9 @@
 from chromite.lib import patch as cros_patch
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class GerritException(Exception):
   """Base exception, thrown for gerrit failures"""
 
diff --git a/lib/gerrit_unittest b/lib/gerrit_unittest
deleted file mode 120000
index 72196ce..0000000
--- a/lib/gerrit_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/gerrit_unittest.py b/lib/gerrit_unittest.py
index 3e96608..4e5095d 100644
--- a/lib/gerrit_unittest.py
+++ b/lib/gerrit_unittest.py
@@ -15,6 +15,7 @@
 import re
 import shutil
 import stat
+import sys
 
 import mock
 import six
@@ -33,6 +34,9 @@
 from chromite.lib import retry_util
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 class GerritTestCase(cros_test_lib.MockTempDirTestCase):
   """Test class for tests that interact with a Gerrit server.
 
diff --git a/lib/patch.py b/lib/patch.py
index 218f824..14d56c7 100644
--- a/lib/patch.py
+++ b/lib/patch.py
@@ -13,6 +13,7 @@
 import random
 import re
 import subprocess
+import sys
 import time
 
 import six
@@ -33,6 +34,9 @@
   mock = None
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 _MAXIMUM_GERRIT_NUMBER_LENGTH = 7
 _GERRIT_CHANGE_ID_PREFIX = 'I'
 _GERRIT_CHANGE_ID_LENGTH = 40
diff --git a/lib/patch_unittest b/lib/patch_unittest
deleted file mode 120000
index 72196ce..0000000
--- a/lib/patch_unittest
+++ /dev/null
@@ -1 +0,0 @@
-../scripts/wrapper.py
\ No newline at end of file
diff --git a/lib/patch_unittest.py b/lib/patch_unittest.py
index 8bb3a28..ca02a7f 100644
--- a/lib/patch_unittest.py
+++ b/lib/patch_unittest.py
@@ -12,6 +12,7 @@
 import itertools
 import os
 import shutil
+import sys
 import tempfile
 import time
 
@@ -27,6 +28,9 @@
 from chromite.lib import patch as cros_patch
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 _GetNumber = functools.partial(next, itertools.count())
 
 # Change-ID of a known open change in public gerrit.
diff --git a/scripts/run_tests.py b/scripts/run_tests.py
index d86a48a..a4ccac9 100644
--- a/scripts/run_tests.py
+++ b/scripts/run_tests.py
@@ -80,8 +80,6 @@
 SLOW_TESTS = {
     # Tests that require network can be really slow.
     'lib/cros_build_lib_unittest': SKIP,
-    'lib/gerrit_unittest': SKIP,
-    'lib/patch_unittest': SKIP,
 }
 
 
diff --git a/scripts/run_tests_unittest.py b/scripts/run_tests_unittest.py
index f467b6e..50e0d05 100644
--- a/scripts/run_tests_unittest.py
+++ b/scripts/run_tests_unittest.py
@@ -167,7 +167,7 @@
     """Verify --quick filters out slow tests"""
     self.PatchObject(run_tests, 'RunTests', return_value=True)
     # Pick a test that is in SLOW_TESTS but not in SPECIAL_TESTS.
-    slow_test = 'lib/patch_unittest'
+    slow_test = 'lib/cros_build_lib_unittest'
     self.assertIn(slow_test, run_tests.SLOW_TESTS)
     self.assertNotIn(slow_test, run_tests.SPECIAL_TESTS)
     run_tests.main(['--quick'])