[BUG] Diff on revision range for branch in repository without working trees is not possible

[Nicholas Allen]

I submitted a bug on this https://bugs.launchpad.net/bzr/+bug/84236 as 
from a user's point of view (at least this user anyway) it seems like a 
bug. The fact it is inconsistent with the log command seems strange too. 
Anything you can show the log for I think you should be able to show the 
diffs for.

Nick