Catch locale.error as well. Fixes #788378. Will backport to 2.3.
diff --git a/Lib/idlelib/IOBinding.py b/Lib/idlelib/IOBinding.py
index 0c3ae7f..391be77 100644
--- a/Lib/idlelib/IOBinding.py
+++ b/Lib/idlelib/IOBinding.py
@@ -29,7 +29,7 @@
 try:
     import locale
     locale.setlocale(locale.LC_CTYPE, "")
-except ImportError:
+except (ImportError, locale.error):
     pass
 
 encoding = "ascii"