Fix %edit - editor attribute was missing

IPython/terminal/ptshell.py

@@ -25,6 +25,7 b' from pygments.lexers import Python3Lexer, PythonLexer'
 from pygments.token import Token
 
 from .pt_inputhooks import get_inputhook_func
+from .interactiveshell import get_default_editor
 
 
 class IPythonPTCompleter(Completer):
@@ -61,6 +62,10 b' class PTInteractiveShell(InteractiveShell):'
         help="Override highlighting format for specific tokens"
     )
 
+    editor = Unicode(get_default_editor(), config=True,
+        help="Set the editor used by IPython (default to $EDITOR/vi/notepad)."
+    )
+
     def get_prompt_tokens(self, cli):
         return [
             (Token.Prompt, 'In ['),