Use os.devnull instead of hardcoded '/dev/null'.

Lib/test/test_cgi.py

@@ -194,9 +194,9 @@ class CgiTests(unittest.TestCase):
         cgi.initlog("%s", "Testing initlog 1")
         cgi.log("%s", "Testing log 2")
         self.assertEqual(cgi.logfp.getvalue(), "Testing initlog 1\nTesting log 2\n")
-        if os.path.exists("/dev/null"):
+        if os.path.exists(os.devnull):
             cgi.logfp = None
-            cgi.logfile = "/dev/null"
+            cgi.logfile = os.devnull
             cgi.initlog("%s", "Testing log 3")
             cgi.log("Testing log 4")
 

Lib/test/test_sysconfig.py

@@ -294,7 +294,7 @@ class TestSysConfig(unittest.TestCase):
         if 'MACOSX_DEPLOYMENT_TARGET' in env:
             del env['MACOSX_DEPLOYMENT_TARGET']
 
-        with open('/dev/null', 'w') as devnull_fp:
+        with open(os.devnull, 'w') as devnull_fp:
             p = subprocess.Popen([
                     sys.executable, '-c',
                    'import sysconfig; print(sysconfig.get_platform())',
@@ -320,7 +320,7 @@ class TestSysConfig(unittest.TestCase):
                 'import sysconfig; print(sysconfig.get_platform())',
             ],
             stdout=subprocess.PIPE,
-            stderr=open('/dev/null'),
+            stderr=open(os.devnull),
             env=env)
         test_platform = p.communicate()[0].strip()
         test_platform = test_platform.decode('utf-8')

Tools/compiler/compile.py

+import os
 import sys
 import getopt
 
@@ -16,11 +17,7 @@ def main():
             VERBOSE = 1
             visitor.ASTVisitor.VERBOSE = visitor.ASTVisitor.VERBOSE + 1
         if k == '-q':
-            if sys.platform[:3]=="win":
-                f = open('nul', 'wb') # /dev/null fails on Windows...
-            else:
-                f = open('/dev/null', 'wb')
-            sys.stdout = f
+            sys.stdout = open(os.devnull, 'wb')
         if k == '-d':
             DISPLAY = 1
         if k == '-c':