Fix pep8 errors

Pep8 job is broken due to recent pep8 upgrade and corresponding
pycodestyle update.

This commit fixes the following errors:
  - E731 do not assign a lambda expression, use a def
  - W503 line break before binary operator
  - E402 module level import not at top of file

Change-Id: Ib357336eb165cf642f6793ff6cdde7d53075b158

neutron_vpnaas/db/migration/alembic_migrations/versions/3ea02b2a773e_add_index_tenant_id.py

@@ -21,12 +21,12 @@ Create Date: 2015-02-10 17:51:10.752504
 
 """
 
+from alembic import op
+
 # revision identifiers, used by Alembic.
 revision = '3ea02b2a773e'
 down_revision = 'start_neutron_vpnaas'
 
-from alembic import op
-
 TABLES = ['ipsecpolicies', 'ikepolicies', 'ipsec_site_connections',
           'vpnservices']
 

neutron_vpnaas/db/migration/alembic_migrations/versions/liberty/contract/333dfd6afaa2_populate_vpn_service_table_fields.py

@@ -21,16 +21,14 @@ Create Date: 2015-07-27 16:43:59.123456
 
 """
 
-# revision identifiers, used by Alembic.
-revision = '333dfd6afaa2'
-down_revision = '56893333aa52'
-depends_on = '24f28869838b'
-
-
 from alembic import op
 import netaddr
 import sqlalchemy as sa
 
+# revision identifiers, used by Alembic.
+revision = '333dfd6afaa2'
+down_revision = '56893333aa52'
+depends_on = '24f28869838b'
 
 VPNService = sa.Table('vpnservices', sa.MetaData(),
                       sa.Column('router_id', sa.String(36), nullable=False),

neutron_vpnaas/db/migration/alembic_migrations/versions/mitaka/expand/41b509d10b5e_vpnaas_endpoint_groups.py

@@ -20,15 +20,15 @@ Create Date: 2015-08-06 18:21:03.241664
 
 """
 
-# revision identifiers, used by Alembic.
-revision = '41b509d10b5e'
-down_revision = '24f28869838b'
-
 from alembic import op
 import sqlalchemy as sa
 
 from neutron_vpnaas.services.vpn.common import constants
 
+# revision identifiers, used by Alembic.
+revision = '41b509d10b5e'
+down_revision = '24f28869838b'
+
 
 def upgrade():
     op.create_table(

neutron_vpnaas/db/migration/alembic_migrations/versions/pike/expand/95601446dbcc_add_flavor_id_to_vpnservices.py

@@ -21,15 +21,14 @@ Create Date: 2017-04-10 10:14:41.724811
 
 """
 
-# revision identifiers, used by Alembic.
-revision = '95601446dbcc'
-down_revision = '38893903cbde'
-
 from alembic import op
 import sqlalchemy as sa
 
 from neutron.db import migration
 
+# revision identifiers, used by Alembic.
+revision = '95601446dbcc'
+down_revision = '38893903cbde'
 
 # milestone identifier, used by neutron-db-manage
 neutron_milestone = [migration.PIKE]

neutron_vpnaas/db/vpn/vpn_db.py

@@ -683,8 +683,8 @@ class VPNPluginRpcDbMixin(object):
                                 vpnservice['id'])
                     continue
 
-                if (not utils.in_pending_status(vpnservice_db.status)
-                    or vpnservice['updated_pending_status']):
+                if (not utils.in_pending_status(vpnservice_db.status) or
+                    vpnservice['updated_pending_status']):
                     vpnservice_db.status = vpnservice['status']
                 for conn_id, conn in vpnservice[
                     'ipsec_site_connections'].items():

neutron_vpnaas/tests/unit/services/vpn/device_drivers/test_ipsec.py

@@ -343,8 +343,7 @@ class BaseIPsecDeviceDriver(base.BaseTestCase):
     @staticmethod
     def generate_diff(a, b):
         """Generates unified diff of a and b."""
-        by_lines = lambda x: x.splitlines(True)
-        a, b = list(by_lines(a)), list(by_lines(b))
+        a, b = list(a.splitlines(True)), list(b.splitlines(True))
         diff = difflib.unified_diff(a, b, fromfile="expected",
                                     tofile="actual")
         return diff