[PATCH 0 of 4] cmdutil.walkchangerevs fixes (issue732)

[Nicolas Dumazet]

Hello -devel!

I had the chance to learn about the beauties of walkchangerevs during the last
hours, when trying to fix issue732 :)
While the general windowed algorithm is a very interesting idea, I do think
that it needs a few fixes.

* First patch is an easy, no-brainer cosmetic fix
* #2 and #3 are revision range tweaks that allow us to walk less filelog nodes
  than what we currently do
* #4 is the actual bugfix. It should not induce any performance regression:
  if I'm correct, filelog.renamed() already does the same (parents[0] == nullid)
  check


Thanks for your reviews,

Nicolas.