[gitk bug] 'invalid command name ".bleft.ctext"' when exiting gitk

If I run "./gitk" on the current git master
(c94bf41c9a78dc1c084f2a2895f95b6b6d8f79b1), and hit Ctrl-Q shortly
after gitk starts to fill the diff pane, I get the following error on
the tty:

|invalid command name ".bleft.ctext"
|    while executing
|"$ctext conf -state normal"
|    (procedure "dispneartags" line 7)
|    invoked from within
|"dispneartags"
|    (procedure "restartatags" line 31)
|    invoked from within
|"restartatags"
|    ("after" script)

This problem is not easy to reproduce at every try, I have to try
several times to see it, but it's still pretty easy to get the error.

Anyone knows what it's trying to do ?  Is that a race condition
between "after idle restartatags" and the widgets being destroyed ?

-- 
Yann.