This function fetches origin with a Force flag set to true, which causes all local branches to be updated to match their remote counterparts.

This function is thought over the fact that the most recent commit of a git repository is one of its leafs.

comparatorFunc is a comparator function that has to be understood in analogy to <(a, b), where a and b are numbers and "<" is a comparator function that returns true if a < b and false otherwise.