Merge branch 'separate-prelim-options' into 'master'

Separate pre-configuration CLI parsing

See merge request pycqa/flake8!364

tests/integration/test_aggregator.py

@@ -1,4 +1,5 @@
 """Test aggregation of config files and command-line options."""
+import argparse
 import os
 
 import pytest
@@ -14,9 +15,12 @@ CLI_SPECIFIED_CONFIG = 'tests/fixtures/config_files/cli-specified.ini'
 @pytest.fixture
 def optmanager():
     """Create a new OptionManager."""
+    prelim_parser = argparse.ArgumentParser(add_help=False)
+    options.register_preliminary_options(prelim_parser)
     option_manager = manager.OptionManager(
         prog='flake8',
         version='3.0.0',
+        parents=[prelim_parser],
     )
     options.register_default_options(option_manager)
     return option_manager