#1087: use proper skips in test_os.

Lib/test/test_os.py

@@ -514,16 +514,16 @@ class EnvironTests(mapping_tests.BasicTestMappingProtocol):
         return os.environ
 
     # Bug 1110478
+    @unittest.skipUnless(os.path.exists('/bin/sh'), 'requires /bin/sh')
     def test_update2(self):
         os.environ.clear()
-        if os.path.exists("/bin/sh"):
         os.environ.update(HELLO="World")
         with os.popen("/bin/sh -c 'echo $HELLO'") as popen:
             value = popen.read().strip()
             self.assertEqual(value, "World")
 
+    @unittest.skipUnless(os.path.exists('/bin/sh'), 'requires /bin/sh')
     def test_os_popen_iter(self):
-        if os.path.exists("/bin/sh"):
         with os.popen(
             "/bin/sh -c 'echo \"line1\nline2\nline3\"'") as popen:
             it = iter(popen)