Fix off-by-one error in Tim's recent change to comment_region(): the

list of lines returned by get_region() contains an empty line at the
end representing the start of the next line, and this shouldn't be
commented out!

Tools/idle/AutoIndent.py

@@ -347,7 +347,7 @@ class AutoIndent:
 
     def comment_region_event(self, event):
         head, tail, chars, lines = self.get_region()
-        for pos in range(len(lines)):
+        for pos in range(len(lines) - 1):
             line = lines[pos]
             lines[pos] = '##' + line
         self.set_region(head, tail, chars, lines)