[MERGE][#144421][#144300] Use write lock in log and status with '-r branch:URL'

[John Arbash Meinel]

John Arbash Meinel has voted comment.
Status is now: Semi-approved
Comment:
I changed my mind....
I'm hesitant about this patch because I see it as a hack on top of a 
hack. The first being that "branch:" pulls revisions into the local 
repository, and the second making a readonly operation like status/diff 
become a read-write operation as a side-effect of what revision you are 
comparing against.

I think the correct fix is to have revision specs which reference a 
second branch have the ability to add a revision source to the rest of 
the query functions. That way we don't have to do any writing during a 
read-only operation.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C1198950827.6593.3.camel%40nemo%3E