[MERGE] More than double the speed of "bzr selftest"

[John Arbash Meinel]

John Arbash Meinel has voted +1.
Status is now: Approved
Comment:
My only concerns are:

1) leaving stuff cluttering $TEMP if the rmtree fails
2) running out of path space on Win32 because IIRC, TEMP is in:
     C:\Documents and Settings\<username>\Local Settings\Temp

However, if we are going to leave clutter, it is best to put it in '.' 
or TEMP, so I'm okay with this.

Ian- do you want this for 0.17? As a change to the test infrastructure I 
consider it safe enough, but that is my personal opinion.


For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3Ce01316480706061519qd103626id95ab60b8af5860d%40mail.gmail.com%3E