title: Why would you used '--track' options in git branches?
body: <p>This is my understanding about tracking git branches, please correct me if I am missing something here. To track a remote branch, you would first run <code>git fetch origin</code>, which brings a copy image of the remote git repository. Let's say you list the branches you want to create a tacking branch to <code>mybranch</code>, you'd simply run <code>git branch mybranch</code> and then git will automatically create a remote branch and make it tracking the corresponding (name correlation) remote branch. Very simple! 
  The question is, why do most of the git folks talk about the option <code>--track</code> if git is capable to identify the branch you just create (based on name correlation) is available in <code>origin</code> or remote repository? </p>