Issue #16826: Revert fix while Windows issues are being worked out.

Lib/importlib/_bootstrap.py

@@ -29,10 +29,7 @@ def _make_relax_case():
     if sys.platform.startswith(_CASE_INSENSITIVE_PLATFORMS):
         def _relax_case():
             """True if filenames must be checked case-insensitively."""
-            if sys.flags.ignore_environment:
-                return False
-            else:
-                return b'PYTHONCASEOK' in _os.environ
+            return b'PYTHONCASEOK' in _os.environ
     else:
         def _relax_case():
             """True if filenames must be checked case-insensitively."""

Lib/test/test_importlib/extension/test_case_sensitivity.py

@@ -6,8 +6,7 @@ from importlib import _bootstrap
 from importlib import machinery
 from .. import util
 from . import util as ext_util
-import os
-import subprocess
+
 
 @util.case_insensitive_tests
 class ExtensionModuleCaseSensitivityTest(unittest.TestCase):
@@ -31,34 +30,14 @@ class ExtensionModuleCaseSensitivityTest(unittest.TestCase):
             self.assertIsNone(loader)
 
     def test_case_insensitivity(self):
-        find_snippet = """if True:
-            from importlib import _bootstrap
-            import sys
-            finder = _bootstrap.FileFinder('{path}',
-                                           (_bootstrap.ExtensionFileLoader,
-                                            _bootstrap.EXTENSION_SUFFIXES))
-            loader = finder.find_module('{bad_name}')
-            print(str(hasattr(loader, 'load_module')))
-            """.format(bad_name=ext_util.NAME.upper(), path=ext_util.PATH)
+        with support.EnvironmentVarGuard() as env:
+            env.set('PYTHONCASEOK', '1')
+            if b'PYTHONCASEOK' not in _bootstrap._os.environ:
+                self.skipTest('os.environ changes not reflected in '
+                              '_os.environ')
+            loader = self.find_module()
+            self.assertTrue(hasattr(loader, 'load_module'))
 
-        newenv = os.environ.copy()
-        newenv["PYTHONCASEOK"] = "1"
-
-        def check_output(expected, extra_arg=None):
-            args = [sys.executable]
-            if extra_arg:
-                args.append(extra_arg)
-            args.extend(["-c", find_snippet])
-            p = subprocess.Popen(args, stdout=subprocess.PIPE, env=newenv)
-            actual = p.communicate()[0].decode().strip()
-            self.assertEqual(expected, actual)
-            self.assertEqual(p.wait(), 0)
-
-        # Test with PYTHONCASEOK=1.
-        check_output("True")
-
-        # Test with PYTHONCASEOK=1 ignored because of -E.
-        check_output("False", "-E")
 
 
 

Lib/test/test_importlib/source/test_case_sensitivity.py

@@ -8,7 +8,6 @@ import os
 import sys
 from test import support as test_support
 import unittest
-import subprocess
 
 
 @util.case_insensitive_tests
@@ -51,62 +50,16 @@ class CaseSensitivityTest(unittest.TestCase):
             self.assertIsNone(insensitive)
 
     def test_insensitive(self):
-        sensitive_pkg = 'sensitive.{0}'.format(self.name)
-        insensitive_pkg = 'insensitive.{0}'.format(self.name.lower())
-        context = source_util.create_modules(insensitive_pkg, sensitive_pkg)
-        with context as mapping:
-            sensitive_path = os.path.join(mapping['.root'], 'sensitive')
-            insensitive_path = os.path.join(mapping['.root'], 'insensitive')
-            find_snippet = """if True:
-                import sys
-                from importlib import machinery
-
-                def find(path):
-                    f = machinery.FileFinder(path,
-                                             (machinery.SourceFileLoader,
-                                              machinery.SOURCE_SUFFIXES),
-                                             (machinery.SourcelessFileLoader,
-                                              machinery.BYTECODE_SUFFIXES))
-                    return f.find_module('{name}')
-
-                sensitive = find('{sensitive_path}')
-                insensitive = find('{insensitive_path}')
-                print(str(hasattr(sensitive, 'load_module')))
-                if hasattr(sensitive, 'load_module'):
-                    print(sensitive.get_filename('{name}'))
-                else:
-                    print('None')
-                print(str(hasattr(insensitive, 'load_module')))
-                if hasattr(insensitive, 'load_module'):
-                    print(insensitive.get_filename('{name}'))
-                else:
-                    print('None')
-                """.format(sensitive_path=sensitive_path,
-                           insensitive_path=insensitive_path,
-                           name=self.name)
-
-            newenv = os.environ.copy()
-            newenv["PYTHONCASEOK"] = "1"
-
-            def check_output(expected, extra_arg=None):
-                args = [sys.executable]
-                if extra_arg:
-                    args.append(extra_arg)
-                args.extend(["-c", find_snippet])
-                p = subprocess.Popen(args, stdout=subprocess.PIPE,
-                                         env=newenv)
-                actual = p.communicate()[0].decode().split()
-                self.assertEqual(expected[0], actual[0])
-                self.assertIn(expected[1], actual[1])
-                self.assertEqual(expected[2], actual[2])
-                self.assertIn(expected[3], actual[3])
-                self.assertEqual(p.wait(), 0)
-
-            # Test with PYTHONCASEOK=1.
-            check_output(["True", self.name, "True", self.name])
-
-            # Test with PYTHONCASEOK=1 ignored because of -E.
-            check_output(["True", self.name, "False", "None"], "-E")
+        with test_support.EnvironmentVarGuard() as env:
+            env.set('PYTHONCASEOK', '1')
+            if b'PYTHONCASEOK' not in _bootstrap._os.environ:
+                self.skipTest('os.environ changes not reflected in '
+                              '_os.environ')
+            sensitive, insensitive = self.sensitivity_test()
+            self.assertTrue(hasattr(sensitive, 'load_module'))
+            self.assertIn(self.name, sensitive.get_filename(self.name))
+            self.assertTrue(hasattr(insensitive, 'load_module'))
+            self.assertIn(self.name, insensitive.get_filename(self.name))
 
 
 def test_main():

Misc/NEWS

@@ -54,8 +54,6 @@ Core and Builtins
 Library
 -------
 
-- Issue #16826: Don't check for PYTHONCASEOK if interpreter started with -E.
-
 - Issue #18901: The sunau getparams method now returns a namedtuple rather than
   a plain tuple.  Patch by Claudiu Popa.