Revert "Fixed unit test testDeleteAllItemsFromStringSet"

Hello @sboora, @x-ma, 

I think something crazy was going on? Both Xiao and I are seeing this test as broken
and rolling back fixes it?

Please review the following commits I made in branch 'nick-tests'.

d593d623bf6ddde28f82da8300848c02e3829d5a (2013-11-18 15:41:41 -0500)
Revert "Fixed unit test testDeleteAllItemsFromStringSet"
This reverts commit 66b4e3ed7161c68ece37e694d626cd4aff71127e.

R=@sboora
R=@x-ma