[MERGE] handle null revision properly for LCA

Tue Jun 19 21:37:05 BST 2007

John Arbash Meinel has voted +1.
Status is now: Approved
Comment:
Seems a little spread around considering how narrowly defined the change 
seemed.

However, I'm happy to see us switching to "null:" as the revision_id 
rather than "None" (unknown whether it is Nothing Supplied, or the 
Generator Revision Id).

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C4677EEDD.8000202%40utoronto.ca%3E