Run a Git command on a list of repositories. The arguments after the
known options or -- indicator are used as the arguments for the Git
subprocess.
THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.
For example, we could run maintenance on each of a list of repositories
stored in a maintenance.repo config variable using
git for-each-repo --config=maintenance.repo maintenance run
This will run git -C <repo> maintenance run for each value <repo>
in the multi-valued config variable maintenance.repo.