Fix

[ 924301 ] A leak case with cmd.py & readline & exception

by ensuring that the readline completion function is always reset
even in the case of an exception being raised.  As a bonus, this
makes the documentation for pre & postloop accurate again.

Lib/cmd.py

@@ -107,6 +107,15 @@ class Cmd:
         """
 
         self.preloop()
+        if self.use_rawinput and self.completekey:
+            try:
+                import readline
+                self.old_completer = readline.get_completer()
+                readline.set_completer(self.complete)
+                readline.parse_and_bind(self.completekey+": complete")
+            except ImportError:
+                pass
+        try:
             if intro is not None:
                 self.intro = intro
             if self.intro:
@@ -133,6 +142,14 @@ class Cmd:
                 stop = self.onecmd(line)
                 stop = self.postcmd(stop, line)
             self.postloop()
+        finally:
+            if self.use_rawinput and self.completekey:
+                try:
+                    import readline
+                    readline.set_completer(self.old_completer)
+                except ImportError:
+                    pass
+            
 
     def precmd(self, line):
         """Hook method executed just before the command line is
@@ -147,13 +164,6 @@ class Cmd:
 
     def preloop(self):
         """Hook method executed once when the cmdloop() method is called."""
-        if self.completekey:
-            try:
-                import readline
-                self.old_completer = readline.get_completer()
-                readline.set_completer(self.complete)
-                readline.parse_and_bind(self.completekey+": complete")
-            except ImportError:
         pass
 
     def postloop(self):
@@ -161,11 +171,6 @@ class Cmd:
         return.
 
         """
-        if self.completekey:
-            try:
-                import readline
-                readline.set_completer(self.old_completer)
-            except ImportError:
         pass
     
     def parseline(self, line):