pythongh-143959: Make _datetime optional for test_sys (pythonGH-144003)

Author: youknowone

Lib/test/test_sys.py

@@ -1,6 +1,5 @@
 import builtins
 import codecs
-import _datetime
 import gc
 import io
 import locale
@@ -1742,7 +1741,12 @@ def delx(self): del self.__x
             x = property(getx, setx, delx, "")
             check(x, size('5Pi'))
         # PyCapsule
-        check(_datetime.datetime_CAPI, size('6P'))
+        try:
+            import _datetime
+        except ModuleNotFoundError:
+            pass
+        else:
+            check(_datetime.datetime_CAPI, size('6P'))
         # rangeiterator
         check(iter(range(1)), size('3l'))
         check(iter(range(2**65)), size('3P'))