Update a forked repo with the upstream repo
$ mkdir my_own_project
$ cd my_own_project
$ git init
$ git remote add upstream git@github.com:ORIGINAL_REPO_OWNER/ORIGINAL_REPO_NAME.git
$ git fetch upstream
$ git merge upstream/master
# update:
$ git fetch upstream
$ git pull upstream/master
$ git merge upstream/master
When a string first appeared
git log -S "larry.page@yahoo.fr" --source --all