[MERGE] fix bugs with external_diff

[Martin Pool]

On 31 Jul 2006, John Arbash Meinel <john at arbash-meinel.com> wrote:
> The attached patch fixes a couple bugs in how bzr handles calling out to
> an external diff.

+1.  I'll send a merge request.

> The fix is pretty small and well tested. So I'd like to merge this for
> 0.9. (bzr.dev cannot run an external diff at all because of bug 54651,
> so it is fairly critical)

-- 
Martin