Tidy up pytest-based tests

test_runner/test_broken.py

@@ -4,7 +4,6 @@ import os
 pytest_plugins = ("fixtures.zenith_fixtures")
 
 """
-
 Use this test to see what happens when tests fail.
 
 We should be able to clean up after ourselves, including stopping any
@@ -12,21 +11,21 @@ postgres or pageserver processes.
 
 Set the environment variable RUN_BROKEN to see this test run (and fail,
 and hopefully not leave any server processes behind).
-
 """
 
 
 run_broken = pytest.mark.skipif(
-    os.environ.get('RUN_BROKEN') == None,
+    os.environ.get('RUN_BROKEN') is None,
     reason="only used for testing the fixtures"
 )
 
+
 @run_broken
 def test_broken(zenith_cli, pageserver, postgres, pg_bin):
     # Create a branch for us
-    zenith_cli.run(["branch", "test_broken", "empty"]);
+    zenith_cli.run(["branch", "test_broken", "empty"])
 
-    pg = postgres.create_start("test_broken")
+    postgres.create_start("test_broken")
     print('postgres is running')
 
     print('THIS NEXT COMMAND WILL FAIL:')