[PATCH] mercurial.el: fix error on hg-read-rev() with small tip, and cleanups

[NIIMI Satoshi]

Brendan Cully wrote:
> Pushed, thanks. But it would have been nice if you'd split the patch
> into pieces (say one for each bullet point here).

Thanks for reviewing and pushing the patch.  I'll send patches as you 
write in the future.

-- 
NIIMI Satoshi