Change date of a commit http://stackoverflow.com/questions/454734/how-can-one-change-the-timestamp-of-an-old-commit-in-git#454750

git-cdc

#!/bin/bash
# commit
# date YYYY-mm-dd HH:MM:SS

commit="$1" datecal="$2"
temp_branch="temp-rebasing-branch"
current_branch="$(git rev-parse --abbrev-ref HEAD)"

date_timestamp=$(gdate -d "$datecal" +%s)
date_r=$(gdate -R -d "$datecal")

if [[ -z "$commit" ]]; then
    exit 0
fi

git checkout -b "$temp_branch" "$commit"
GIT_COMMITTER_DATE="$date_timestamp" GIT_AUTHOR_DATE="$date_timestamp" git commit --amend --no-edit --date "$date_r"
git checkout "$current_branch"
git rebase  --autostash --committer-date-is-author-date "$commit" --onto "$temp_branch"
git branch -d "$temp_branch"