Backport of Issue #14409 to 2.7

IDLE doesn't not execute commands from shell with default keybinding
for <Return>.
Patch by Roger Serwy.

Lib/idlelib/NEWS.txt

 What's New in IDLE 2.7.3?
 =======================
 
+- Issue #14409: IDLE doesn't not execute commands from shell,
+  error with default keybinding for Return. (Patch by Roger Serwy)
+
 - Issue #3573: IDLE hangs when passing invalid command line args
   (directory(ies) instead of file(s)).
 

Lib/idlelib/configHandler.py

@@ -595,7 +595,7 @@ class IdleConf:
             '<<replace>>': ['<Control-h>'],
             '<<goto-line>>': ['<Alt-g>'],
             '<<smart-backspace>>': ['<Key-BackSpace>'],
-            '<<newline-and-indent>>': ['<Key-Return> <Key-KP_Enter>'],
+            '<<newline-and-indent>>': ['<Key-Return>', '<Key-KP_Enter>'],
             '<<smart-indent>>': ['<Key-Tab>'],
             '<<indent-region>>': ['<Control-Key-bracketright>'],
             '<<dedent-region>>': ['<Control-Key-bracketleft>'],

Misc/NEWS

@@ -35,6 +35,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #14409: IDLE doesn't not execute commands from shell,
+  error with default keybinding for Return. (Patch by Roger Serwy)
+
 - Issue #10340: asyncore - properly handle EINVAL in dispatcher constructor on
   OSX; avoid to call handle_connect in case of a disconnected socket which
   was not meant to connect.