[1.7.x] Fixed several flake8 errors

Backport of d17a4cb037 from master

django/db/migrations/autodetector.py

@@ -425,7 +425,7 @@ class MigrationAutodetector(object):
                     options=model_state.options,
                     bases=model_state.bases,
                 ),
-                dependencies = dependencies,
+                dependencies=dependencies,
             )
             # Generate operations for each related field
             for name, field in sorted(related_fields.items()):
@@ -524,7 +524,7 @@ class MigrationAutodetector(object):
                     bases=model_state.bases,
                 ),
                 # Depend on the deletion of any possible non-proxy version of us
-                dependencies = dependencies,
+                dependencies=dependencies,
             )
 
     def generate_deleted_models(self):
@@ -815,7 +815,7 @@ class MigrationAutodetector(object):
                         name=model_name,
                         order_with_respect_to=new_model_state.options.get('order_with_respect_to', None),
                     ),
-                    dependencies = dependencies,
+                    dependencies=dependencies,
                 )
 
     def arrange_for_graph(self, changes, graph):

django/db/migrations/optimizer.py

@@ -163,8 +163,8 @@ class MigrationOptimizer(object):
         """
         Folds a CreateModel and a DeleteModel into nothing.
         """
-        if operation.name.lower() == other.name.lower() and \
-            not operation.options.get("proxy", False):
+        if (operation.name.lower() == other.name.lower() and
+                not operation.options.get("proxy", False)):
             return []
 
     def reduce_model_alter_delete(self, operation, other, in_between):

tests/migrations/test_operations.py

@@ -237,8 +237,8 @@ class OperationTests(MigrationTestBase):
         operation = migrations.CreateModel(
             "ProxyPony",
             [],
-            options = {"proxy": True},
-            bases = ("test_crprmo.Pony", ),
+            options={"proxy": True},
+            bases=("test_crprmo.Pony", ),
         )
         new_state = project_state.clone()
         operation.state_forwards("test_crprmo", new_state)