What steps will reproduce the problem?

1. open a file in vim
2. set rnu
3. open a second file using :vs (it must be a second file, opening a second 
view of the same file with ":vs" by itself maintains the rnu setting)

What is the expected output? What do you see instead?

I expect to see relative line numbering in the new window, but instead see the 
default line numbering.

What version of the product are you using? On what operating system?

cloned 7.3 as of today, on OS X Snow Leopard.