Merge branch 'zh/format-patch-fractional-reroll-count'

"git format-patch -v<n>" learned to allow a reroll count that is
not an integer.

* zh/format-patch-fractional-reroll-count:
  format-patch: allow a non-integral version numbers

diff --cc Documentation/git-format-patch.txt
Simple merge

diff --cc builtin/log.c
Simple merge

diff --cc revision.h
Simple merge