Code review comment for lp:~spiv/bzr/faster-revert-593560

That's pretty nice.

Perhaps the news entry can say a bit more about what changed so we can
understand it later: "by not repeatedly building a list of file ids."

I'd like you to add this to the whatsnew-2.3 docs too, under a
performance heading.

In some ways this patch feels incomplete not to have a test or a
prevention of regressions. I guess it is reasonable to keep
all_file_ids for people who want it. But perhaps just measuring
performance is the best way to keep it up, so +1 with those doc
tweaks.

--
Martin