Freeze break request: modify mash configs for f17

[Bill Nottingham]

Kevin Fenzi (kevin at scrye.com) said: 
> This change is needed to mash f17-updates/f17-updates-testing. 
> 
> Since the parent repos don't exist (or updates does but is empty, Everything doesn't exist). 
> 
> Note, in testing this I did a f17-updates-testing push that seemed to work fine. 
> (Please check and confirm). 

Seems OK. We'd want to revert this before release, but after we populate the
initial everything tree.

Bill