Fix --pure. Fixes #1093

setup.py

@@ -39,7 +39,6 @@ if '__pypy__' not in sys.modules and sys.platform != 'win32':
 
 optional = os.environ.get('CIBUILDWHEEL', '0') != '1'
 
-
 ext_modules = [
     Extension('dulwich._objects', ['dulwich/_objects.c'],
               optional=optional),
@@ -49,6 +48,12 @@ ext_modules = [
               optional=optional),
 ]
 
+# Ideally, setuptools would just provide a way to do this
+if '--pure' in sys.argv:
+    sys.argv.remove('--pure')
+    ext_modules = []
+
+
 setup(package_data={'': ['../docs/tutorial/*.txt', 'py.typed']},
       ext_modules=ext_modules,
       tests_require=tests_require)