git で author, committer を一気に書き換える方法
git filter-branch --env-filter \ 'export GIT_AUTHOR_NAME="NAKAMURA Yoshitaka" GIT_AUTHOR_EMAIL="nakamura@example.com"; export GIT_COMMITTER_NAME="${GIT_AUTHOR_NAME}" GIT_COMMITTER_EMAIL="${GIT_AUTHOR_EMAIL}"'
git filter-branch --env-filter \ 'export GIT_AUTHOR_NAME="NAKAMURA Yoshitaka" GIT_AUTHOR_EMAIL="nakamura@example.com"; export GIT_COMMITTER_NAME="${GIT_AUTHOR_NAME}" GIT_COMMITTER_EMAIL="${GIT_AUTHOR_EMAIL}"'