gitup (the git-repo-updater)
gitup is a tool for updating multiple git repositories at once. It is smart enough to handle several remotes, dirty working directories, diverged local branches, detached HEADs, and more. It was originally created to manage a large collection of projects and deal with sporadic internet access.
gitup should work on macOS, Linux, and Windows. You should have the latest version of git and either Python 2.7 or Python 3 installed.

https://github.com/earwig/git-repo-updater