Fix flake8 error

Author: abravalheri

setuptools/command/build.py

@@ -1,4 +1,5 @@
 from distutils.command.build import build as _build
 
+
 class build(_build):
-    pass
+    pass

setuptools/tests/test_build.py

@@ -13,4 +13,4 @@ def test_distribution_gives_setuptools_build_obj(tmpdir_cwd):
         packages=[''],
         package_data={'': ['path/*']},
     ))
-    assert isinstance(dist.get_command_obj("build"), build)
+    assert isinstance(dist.get_command_obj("build"), build)