From 313523ce2dd67db67b7dcbcc5f6d6ca95922b34b Mon Sep 17 00:00:00 2001
From: Steve Dower <steve.dower@microsoft.com>
Date: Sat, 17 Sep 2016 12:22:41 -0700
Subject: [PATCH] Issue #28192: Don't import readline in isolated mode

---
 Lib/site.py           | 12 +++++++-----
 Lib/test/test_site.py |  8 ++------
 Modules/main.c        |  3 ++-
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/Lib/site.py b/Lib/site.py
index 52502667553..b6376357ea3 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -60,7 +60,8 @@
 
 The readline module is also automatically configured to enable
 completion for systems that support it.  This can be overridden in
-sitecustomize, usercustomize or PYTHONSTARTUP.
+sitecustomize, usercustomize or PYTHONSTARTUP.  Starting Python in
+isolated mode (-I) disables automatic readline configuration.
 
 After these operations, an attempt is made to import a module
 named sitecustomize, which can perform arbitrary additional
@@ -491,7 +492,7 @@ def execsitecustomize():
             else:
                 raise
     except Exception as err:
-        if os.environ.get("PYTHONVERBOSE"):
+        if sys.flags.verbose:
             sys.excepthook(*sys.exc_info())
         else:
             sys.stderr.write(
@@ -511,7 +512,7 @@ def execusercustomize():
             else:
                 raise
     except Exception as err:
-        if os.environ.get("PYTHONVERBOSE"):
+        if sys.flags.verbose:
             sys.excepthook(*sys.exc_info())
         else:
             sys.stderr.write(
@@ -538,12 +539,13 @@ def main():
     setquit()
     setcopyright()
     sethelper()
-    enablerlcompleter()
+    if not sys.flags.isolated:
+        enablerlcompleter()
     execsitecustomize()
     if ENABLE_USER_SITE:
         execusercustomize()
 
-# Prevent edition of sys.path when python was started with -S and
+# Prevent extending of sys.path when python was started with -S and
 # site is imported later.
 if not sys.flags.no_site:
     main()
diff --git a/Lib/test/test_site.py b/Lib/test/test_site.py
index 9afa56eb735..b0486482267 100644
--- a/Lib/test/test_site.py
+++ b/Lib/test/test_site.py
@@ -140,8 +140,6 @@ def test_addpackage_import_bad_exec(self):
         self.assertRegex(err_out.getvalue(), 'Traceback')
         self.assertRegex(err_out.getvalue(), 'ModuleNotFoundError')
 
-    @unittest.skipIf(sys.platform == "win32", "Windows does not raise an "
-                      "error for file paths containing null characters")
     def test_addpackage_import_bad_pth_file(self):
         # Issue 5258
         pth_dir, pth_fn = self.make_pth("abc\x00def\n")
@@ -447,10 +445,9 @@ def test_startup_imports(self):
         popen = subprocess.Popen([sys.executable, '-I', '-v', '-c',
                                   'import sys; print(set(sys.modules))'],
                                  stdout=subprocess.PIPE,
-                                 stderr=subprocess.PIPE)
+                                 stderr=subprocess.PIPE,
+                                 encoding='utf-8')
         stdout, stderr = popen.communicate()
-        stdout = stdout.decode('utf-8')
-        stderr = stderr.decode('utf-8')
         modules = eval(stdout)
 
         self.assertIn('site', modules)
@@ -474,6 +471,5 @@ def test_startup_imports(self):
         if sys.platform != 'darwin':
             self.assertFalse(modules.intersection(collection_mods), stderr)
 
-
 if __name__ == "__main__":
     unittest.main()
diff --git a/Modules/main.c b/Modules/main.c
index 0b82f480a6a..6986d94b42d 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -703,7 +703,8 @@ Py_Main(int argc, wchar_t **argv)
     PySys_SetArgv(argc-_PyOS_optind, argv+_PyOS_optind);
 
     if ((Py_InspectFlag || (command == NULL && filename == NULL && module == NULL)) &&
-        isatty(fileno(stdin))) {
+        isatty(fileno(stdin)) &&
+        !Py_IsolatedFlag) {
         PyObject *v;
         v = PyImport_ImportModule("readline");
         if (v == NULL)