Fix recently introduced test cases.
For datetime, gentoo didn't seem to mind the %e format for strftime.  So, we just excercise those instead making sure that we don't crash.
For test_os, two cases were incorrect.
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index c89a23f..4702e7c 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -559,11 +559,11 @@
 
     def test_fchown(self):
         if hasattr(os, "fchown"):
-            self.assertRaises(OSError, os.fchmod, 10, -1, -1)
+            self.assertRaises(OSError, os.fchown, 10, -1, -1)
 
     def test_fpathconf(self):
         if hasattr(os, "fpathconf"):
-            self.assertRaises(OSError, os.fpathconf, 10, "foo")
+            self.assertRaises(OSError, os.fpathconf, 10, "PC_FILESIZEBITS")
 
     def test_ftruncate(self):
         if hasattr(os, "ftruncate"):