Update hacking for Python3

The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.

blacklist:
 W504 line break after binary operator

Fix:
E305 expected 2 blank lines after class or function definition, found 1

Change-Id: I56d62f67914f07e7aef74f857c4b42e3bfd3416e

oslo_db/sqlalchemy/enginefacade.py

@@ -1076,6 +1076,7 @@ class _TransactionContextManager(object):
 def async_compat(self):
     return self.async_
 
+
 setattr(
     _TransactionContextManager,
     "async", async_compat

oslo_db/sqlalchemy/exc_filters.py

@@ -427,6 +427,7 @@ def _raise_for_all_others(error, match, engine_name, is_disconnect):
     LOG.warn('DB exception wrapped.', exc_info=True)
     raise exception.DBError(error)
 
+
 ROLLBACK_CAUSE_KEY = 'oslo.db.sp_rollback_cause'
 
 

oslo_db/sqlalchemy/utils.py

@@ -1026,6 +1026,7 @@ class DialectMultiFunctionDispatcher(DialectFunctionDispatcher):
                     "Return value not allowed for "
                     "multiple filtered function")
 
+
 dispatch_for_dialect = DialectFunctionDispatcher.dispatch_for_dialect
 
 

oslo_db/tests/sqlalchemy/base.py

@@ -25,6 +25,7 @@ from oslotest import base as test_base
 class Context(object):
     pass
 
+
 context = Context()
 
 

test-requirements.txt

@@ -1,7 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-hacking>=1.1.0,<1.2.0 # Apache-2.0
+hacking>=3.0,<3.1.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 eventlet!=0.18.3,!=0.20.1,>=0.18.2 # MIT
 fixtures>=3.0.0 # Apache-2.0/BSD

tox.ini

@@ -63,7 +63,7 @@ commands =
 
 [flake8]
 # E123, E125 skipped as they are invalid PEP-8.
-ignore = E123,E125
+ignore = E123,E125,W504
 show-source = True
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build