Support __init__.pyw in imported packages.

Author: serhiy-storchaka

Lib/_py_warnings.py

@@ -534,11 +534,12 @@ def _match_filename(pattern, filename, *, MS_WINDOWS=(sys.platform == 'win32')):
     if pattern.match(filename):  # for backward compatibility
         return True
     if MS_WINDOWS:
+        if not is_py and filename[-4:].lower() == '.pyw':
+            filename = filename[:-4]
+            is_py = True
         if is_py and filename[-9:].lower() in (r'\__init__', '/__init__'):
             filename = filename[:-9]
-        elif not is_py and filename[-4:].lower() == '.pyw':
-            filename = filename[:-4]
-        filename = filename.replace('\\', '.')
+        filename = filename.replace('\\', '/')
     else:
         if is_py and filename.endswith('/__init__'):
             filename = filename[:-9]

Lib/test/test_cmd_line.py

@@ -198,7 +198,7 @@ def test_run_module_bug1764407(self):
         p.stdin.write(b'Timer\n')
         p.stdin.write(b'exit()\n')
         data = kill_python(p)
-        self.assertIn(b'1 loop', data)
+        self.assertTrue(data.find(b'1 loop') != -1)
         self.assertTrue(data.find(b'__main__.Timer') != -1)
 
     def test_relativedir_bug46421(self):

Lib/test/test_warnings/__init__.py

@@ -264,6 +264,8 @@ def test_filter_module(self):
                 self.assertEqual(len(w), 6)
                 self.module.warn_explicit('msg', UserWarning, r'C:\path\to\package\module.PYW', 42)
                 self.assertEqual(len(w), 7)
+                self.module.warn_explicit('msg', UserWarning, r'C:\path\to\package\module\__INIT__.PYW', 42)
+                self.assertEqual(len(w), 8)
 
         with self.module.catch_warnings(record=True) as w:
             self.module.simplefilter('error')