application: Ensure -h/--help is unknown during preliminary parsing

Now that the preliminary parser is being used, we can remove needing to
prune out `-h` and `--help` from the copied `args` list.

src/flake8/main/application.py

@@ -129,14 +129,6 @@ class Application(object):
             args.remove("--version")
         except ValueError:
             pass
-        try:
-            args.remove("--help")
-        except ValueError:
-            pass
-        try:
-            args.remove("-h")
-        except ValueError:
-            pass
 
         return self.prelim_arg_parser.parse_known_args(args)
 

tests/unit/test_application.py

@@ -99,6 +99,20 @@ def test_prelim_opts_args(application):
     assert args == ['--foo', 'src', 'setup.py', '--statistics']
 
 
+def test_prelim_opts_ignore_help(application):
+    """Verify -h/--help is not handled."""
+    # GIVEN
+
+    # WHEN
+    _, args = application.parse_preliminary_options_and_args([
+        '--help',
+        '-h',
+    ])
+
+    # THEN
+    assert args == ['--help', '-h']
+
+
 def test_prelim_opts_handles_empty(application):
     """Verify empty argv lists are handled correctly."""
     irrelevant_args = ['myexe', '/path/to/foo']