[AIRFLOW-4198] Remove all try/import compatibility imports (apache#5091)

airflow/contrib/hooks/qubole_check_hook.py

@@ -17,16 +17,14 @@
 # specific language governing permissions and limitations
 # under the License.
 #
+
+from io import StringIO
+
 from airflow.utils.log.logging_mixin import LoggingMixin
 from airflow.contrib.hooks.qubole_hook import QuboleHook
 from airflow.exceptions import AirflowException
 from qds_sdk.commands import Command
 
-try:
-    from cStringIO import StringIO
-except ImportError:
-    from io import StringIO
-
 
 COL_DELIM = '\t'
 ROW_DELIM = '\r\n'

airflow/utils/decorators.py

@@ -17,23 +17,18 @@
 # specific language governing permissions and limitations
 # under the License.
 #
-import os
 
-# inspect.signature is only available in Python 3. funcsigs.signature is
-# a backport.
-try:
-    import inspect
-    signature = inspect.signature
-except AttributeError:
-    import funcsigs
-    signature = funcsigs.signature
+import inspect
+import os
 
 from copy import copy
 from functools import wraps
 
 from airflow import settings
 from airflow.exceptions import AirflowException
 
+signature = inspect.signature
+
 
 def apply_defaults(func):
     """

dev/airflow-pr

@@ -35,12 +35,7 @@ import re
 import subprocess
 import sys
 import textwrap
-
-# Python 3 compatibility
-try:
-    import urllib2 as urllib
-except ImportError:
-    import urllib.request as urllib
+import urllib.request as urllib
 
 try:
     import click

tests/compat.py

@@ -16,10 +16,8 @@
 # KIND, either express or implied.  See the License for the
 # specific language governing permissions and limitations
 # under the License.
-try:
-    from unittest import mock  # noqa: F401
-except ImportError:
-    import mock  # type: ignore  # noqa: F401
+
+from unittest import mock  # noqa: F401
 
 patch = mock.patch
 Mock = mock.Mock

tests/contrib/hooks/test_gcp_api_base_hook.py

@@ -20,6 +20,7 @@
 
 import os
 import unittest
+from io import StringIO
 
 from parameterized import parameterized
 from google.api_core.exceptions import RetryError, AlreadyExists
@@ -36,11 +37,6 @@
 from airflow.hooks.base_hook import BaseHook
 from tests.compat import mock
 
-try:
-    from StringIO import StringIO
-except ImportError:
-    from io import StringIO
-
 
 default_creds_available = True
 default_project = None

tests/contrib/hooks/test_grpc_hook.py

@@ -12,10 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import unittest
-try:
-    from StringIO import StringIO
-except ImportError:
-    from io import StringIO
+from io import StringIO
 
 from airflow import configuration
 from airflow.exceptions import AirflowConfigException

tests/core.py

@@ -24,6 +24,7 @@
 import mock
 import multiprocessing
 import os
+import pickle  # type: ignore
 import re
 import signal
 import sqlalchemy
@@ -75,12 +76,6 @@
 TEST_DAG_ID = 'unit_tests'
 EXAMPLE_DAG_DEFAULT_DATE = days_ago(2)
 
-try:
-    import cPickle as pickle
-except ImportError:
-    # Python 3
-    import pickle  # type: ignore
-
 
 class OperatorSubclass(BaseOperator):
     """