incorrect display when insert/delete characters into a pending command

[GoogleCodeExporter]

What steps will reproduce the problem?
1. open tcsh in conque in a vim
2. input a string after the tcsh prompt
3. move the cursor to delete or insert some characters into the string

What is the expected output? What do you see instead?
The cmd string should update automatically based on the inserted/deleted char. 
But instead, the display of the new string is incorrect.

What version of the product are you using? On what operating system?
redhat linux, gvim 7.4.

Please provide any additional information below.
delete and insert work correctly in the other buffers.

Original issue reported on code.google.com by [email protected] on 6 Dec 2013 at 11:07