[MERGE] Initialize before transfer for BzrDir.clone() and sprout()

[Aaron Bentley]

Aaron Bentley has voted -0.
Status is now: Semi-approved
Comment:
Instead of creating a blank branch, how about creating temp directories 
and moving them into place once they're properly initialized.  That 
seems simpler and very hard to break.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C458B19D2.3090704%40arbash-meinel.com%3E