skip %HOME% 3.8 test on windows, update docs for get_home_dir

IPython/utils/path.py

@@ -175,7 +175,8 b' def get_home_dir(require_writable=False):'
     Uses os.path.expanduser('~'), and checks for writability.
 
     See stdlib docs for how this is determined.
-    $HOME is first priority on *ALL* platforms.
+    For Python <3.8, $HOME is first priority on *ALL* platforms.
+    For Python >=3.8 on Windows, %HOME% is no longer considered.
 
     Parameters
     ----------

IPython/utils/tests/test_path.py

@@ -128,6 +128,7 b' def test_get_home_dir_2():'
     nt.assert_equal(home_dir, unfrozen)
 
 
+@skipif(sys.version_info > (3,8) and os.name == 'nt')
 @with_environment
 def test_get_home_dir_3():
     """get_home_dir() uses $HOME if set"""