[MERGE] Change DirStateRevisionTree

[John Arbash Meinel]

John Arbash Meinel has voted resubmit.
Status is now: Resubmit
Comment:
this fixed one case, and opened up a bunch of others to failure.
cases where we did
tree = WT.open()
basis = tree.basis_tree()
del tree

so even the sloppy code was sloppier than I thought

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C497A0CD9.7030005%40arbash-meinel.com%3E
Project: Bazaar