Re: [PATCH 1/3] treewalk.c: Rename variable ret to cb_bits and remove some dead lines.

The "ret" was meant to mean "the return value we got from the
callback function", not "the return value we would give our caller".

This rename is a bit misleading in that "cb_bits == -1" does not
mean "full bits set", and it does not tell us much what these "bits"
signify.

They are used to answer this question: which one of the trees in
t[0..n] did the callback function consumed (hence needs their
pointers updated).

So perhaps call it "trees_used" or something?

By the way, our log message usually do not Capitalize the subject
after the "<area>:", i.e. do something like this instead:

    Subject: [PATCH 1/3] traverse_trees(): clarify return value of the callback

Thanks.