ぐだぐだな branchを gitを駆使して綺麗にする。 ref: http://qiita.com/dagezi/items/2b73743c237f5f4901f7

file0.txt

- A  [*] (master trunk)
   \- B0 - B1 - B2 (messy_branch)

file1.txt

git checkout messy_branch
git reset master
git add files   # stage necessary files!
git commit -m 'squashed!'

file2.txt

git checkout master
git checkout -b refactor_branch

file3.txt

- A (master)
  |\- B99 (messy_branch)
   \.     [*] (refactor_branch)

file4.txt

git checkout -p messy_branch

file5.txt

- A (master)
  |\- B99 (messy_branch)
   \- C0  [*] (refactor_branch)

file6.txt

git checkout messy_branch
git rebase refactor_branch

file7.txt

- A (master)
   \- C0      (refactor_branch)
       \- B98 [*] (messy_branch)

file8.txt

- A (master)
   \- C0 - C2 - C3 - C1 - C4 (refactor_branch)
                      \- B95 [*] (messy_branch)