compare singletons by identity not equality (closes #16712)

Patch from Serhiy Storchaka.

7 files changed, 9 insertions, 9 deletions

diff --git a/Lib/os.py b/Lib/os.py
index 842512a..84eeaeb 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -985,7 +985,7 @@ def popen(cmd, mode="r", buffering=-1):
         raise TypeError("invalid cmd type (%s, expected string)" % type(cmd))
     if mode not in ("r", "w"):
         raise ValueError("invalid mode %r" % mode)
-    if buffering == 0 or buffering == None:
+    if buffering == 0 or buffering is None:
         raise ValueError("popen() does not support unbuffered streams")
     import subprocess, io
     if mode == "r":
diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index aa296c4..fa531e9 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -2551,8 +2551,8 @@ def cli():
             if opt == '-w':
                 writing = True
 
-        if start_server == True:
-            if port == None:
+        if start_server:
+            if port is None:
                 port = 0
             browse(port, open_browser=open_browser)
             return
diff --git a/Lib/test/support.py b/Lib/test/support.py
index 014bcf5..c5640e0 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -1232,7 +1232,7 @@ def run_with_tz(tz):
             try:
                 return func(*args, **kwds)
             finally:
-                if orig_tz == None:
+                if orig_tz is None:
                     del os.environ['TZ']
                 else:
                     os.environ['TZ'] = orig_tz
diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
index 7028f46..299a146 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -342,7 +342,7 @@ if ssl is not None:
                 # http://www.mail-archive.com/openssl-users@openssl.org/msg60710.html
                 pass
             self._ssl_closing = False
-            if getattr(self, '_ccc', False) == False:
+            if getattr(self, '_ccc', False) is False:
                 super(SSLConnection, self).close()
             else:
                 pass
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index 4e7a37c..f59607b 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -651,7 +651,7 @@ class PosixTester(unittest.TestCase):
             groups = idg.read().strip()
             ret = idg.close()
 
-        if ret != None or not groups:
+        if ret is not None or not groups:
             raise unittest.SkipTest("need working 'id -G'")
 
         self.assertEqual(
@@ -665,7 +665,7 @@ class PosixTester(unittest.TestCase):
             groups = idg.read().strip()
             ret = idg.close()
 
-        if ret != None or not groups:
+        if ret is not None or not groups:
             raise unittest.SkipTest("need working 'id -G'")
 
         # 'id -G' and 'os.getgroups()' should return the same
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 6e0c6ee..e5ec85c 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -897,7 +897,7 @@ class SizeofTest(unittest.TestCase):
         except TypeError:
             tb = sys.exc_info()[2]
             # traceback
-            if tb != None:
+            if tb is not None:
                 check(tb, size('2P2i'))
         # symtable entry
         # XXX
diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index 28f0a2d..f334865 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -736,7 +736,7 @@ class TestCase(object):
             msg: Optional message to use on failure instead of a list of
                     differences.
         """
-        if seq_type != None:
+        if seq_type is not None:
             seq_type_name = seq_type.__name__
             if not isinstance(seq1, seq_type):
                 raise self.failureException('First sequence is not a %s: %s'