when do two names cease to refer to the same string object?

[Farshid Lashkari]

I asked a similar question a few weeks ago. I think the answers I got 
will also answer your question as well. Here's a link to the thread:

http://groups.google.com/group/comp.lang.python/browse_thread/thread/2f6f1d399ba94a7b/f564a219ffe44149?lnk=st&rnum=1&hl=en#f564a219ffe44149

-Farshid