Re: [PATCH 0/3] Speed up remove_redundant()

"Derrick Stolee via GitGitGadget" [off-list ref] writes:

Michael Haggerty pointed out that git merge-base --independent is quite slow
when many commits are provided in the input. This boils down to some
quadratic behavior in remove_redundant() because it calls
paint_down_to_common() in a loop.

This series avoids that by using a single commit walk, pushing a flag that
means "this commit is reachable from a parent of a commit in the list." At
the end of the walk, the input commits without that flag are independent.

Yay.  I've been quite unhappy with the loop ever since I wrote it
back in 2012.

Thanks for cleaning it up.