Revert d370d609d09b as requested by Terry Jan Reedy:

"#3067: locale.setlocale() accepts a Unicode locale."

Lib/locale.py

@@ -525,7 +525,7 @@ def setlocale(category, locale=None):
         category may be given as one of the LC_* values.
 
     """
-    if locale and not isinstance(locale, basestring):
+    if locale and type(locale) is not type(""):
         # convert to string
         locale = normalize(_build_localename(locale))
     return _setlocale(category, locale)

Misc/NEWS

@@ -16,8 +16,6 @@ Core and Builtins
 Library
 -------
 
-- Issue #3067: locale.setlocale() accepts a Unicode locale.
-
 - Issue #11700: mailbox proxy object close methods can now be called multiple
   times without error, and _ProxyFile now closes the wrapped file.